I encountered this yesterday too (FF134.0.1 Win-64).  I had a look in the browser console and saw an error message.  I have not yet had time to investigate any further.
Uncaught TypeError: r.get(...) is not a string
    setValue http://TVH_IP:9981/static/tvh.js.gz:243
    each http://TVH_IP:9981/static/tvh.js.gz:1
    each http://TVH_IP:9981/static/tvh.js.gz:1
    setValue http://TVH_IP:9981/static/tvh.js.gz:243
    initValue http://TVH_IP:9981/static/tvh.js.gz:1
    initValue http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    render http://TVH_IP:9981/static/tvh.js.gz:1
    renderItem http://TVH_IP:9981/static/tvh.js.gz:1
    renderAll http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    runLayout http://TVH_IP:9981/static/tvh.js.gz:1
    onResize http://TVH_IP:9981/static/tvh.js.gz:1
    fire http://TVH_IP:9981/static/tvh.js.gz:1
    fireEvent http://TVH_IP:9981/static/tvh.js.gz:1
    onBodyResize http://TVH_IP:9981/static/tvh.js.gz:1
    onResize http://TVH_IP:9981/static/tvh.js.gz:1
    setSize http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    runLayout http://TVH_IP:9981/static/tvh.js.gz:1
    onResize http://TVH_IP:9981/static/tvh.js.gz:1
    fire http://TVH_IP:9981/static/tvh.js.gz:1
    fireEvent http://TVH_IP:9981/static/tvh.js.gz:1
    onBodyResize http://TVH_IP:9981/static/tvh.js.gz:1
    onResize http://TVH_IP:9981/static/tvh.js.gz:1
    setSize http://TVH_IP:9981/static/tvh.js.gz:1
    setItemSize http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    doLayout http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    render http://TVH_IP:9981/static/tvh.js.gz:1
    show http://TVH_IP:9981/static/tvh.js.gz:1
    success http://TVH_IP:9981/static/tvh.js.gz:702
    success http://TVH_IP:9981/static/tvh.js.gz:1519
    handleResponse http://TVH_IP:9981/static/tvh.js.gz:1
    f http://TVH_IP:9981/static/tvh.js.gz:1
    m http://TVH_IP:9981/static/tvh.js.gz:1
    createCallback http://TVH_IP:9981/static/tvh.js.gz:1
    setInterval handler*n http://TVH_IP:9981/static/tvh.js.gz:1
    i http://TVH_IP:9981/static/tvh.js.gz:1
    request http://TVH_IP:9981/static/tvh.js.gz:1
    request http://TVH_IP:9981/static/tvh.js.gz:1
    Ajax http://TVH_IP:9981/static/tvh.js.gz:1522
    dodirect http://TVH_IP:9981/static/tvh.js.gz:699
    createwin http://TVH_IP:9981/static/tvh.js.gz:709
    idnode_create http://TVH_IP:9981/static/tvh.js.gz:710
    handler http://TVH_IP:9981/static/tvh.js.gz:738
    onClick http://TVH_IP:9981/static/tvh.js.gz:1
    I http://TVH_IP:9981/static/tvh.js.gz:1
    F http://TVH_IP:9981/static/tvh.js.gz:1
    addListener http://TVH_IP:9981/static/tvh.js.gz:1
    m http://TVH_IP:9981/static/tvh.js.gz:1
    h http://TVH_IP:9981/static/tvh.js.gz:1
    addListener http://TVH_IP:9981/static/tvh.js.gz:1
    addListener http://TVH_IP:9981/static/tvh.js.gz:1
    mon http://TVH_IP:9981/static/tvh.js.gz:1
    initButtonEl http://TVH_IP:9981/static/tvh.js.gz:1
    onRender http://TVH_IP:9981/static/tvh.js.gz:1
    render http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    doLayout http://TVH_IP:9981/static/tvh.js.gz:1
    initEvents http://TVH_IP:9981/static/tvh.js.gz:1
    each http://TVH_IP:9981/static/tvh.js.gz:1
    initEvents http://TVH_IP:9981/static/tvh.js.gz:1
    initEvents http://TVH_IP:9981/static/tvh.js.gz:1
    initEvents http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    render http://TVH_IP:9981/static/tvh.js.gz:1
    renderItem http://TVH_IP:9981/static/tvh.js.gz:1
    renderAll http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    doLayout http://TVH_IP:9981/static/tvh.js.gz:1
    build http://TVH_IP:9981/static/tvh.js.gz:764
    success http://TVH_IP:9981/static/tvh.js.gz:768
    success http://TVH_IP:9981/static/tvh.js.gz:1519
tvh.js.gz:243:247
    setValue http://TVH_IP:9981/static/tvh.js.gz:243
    each http://TVH_IP:9981/static/tvh.js.gz:1
    each http://TVH_IP:9981/static/tvh.js.gz:1
    setValue http://TVH_IP:9981/static/tvh.js.gz:243
    initValue http://TVH_IP:9981/static/tvh.js.gz:1
    initValue http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    render http://TVH_IP:9981/static/tvh.js.gz:1
    renderItem http://TVH_IP:9981/static/tvh.js.gz:1
    renderAll http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    runLayout http://TVH_IP:9981/static/tvh.js.gz:1
    onResize http://TVH_IP:9981/static/tvh.js.gz:1
    fire http://TVH_IP:9981/static/tvh.js.gz:1
    fireEvent http://TVH_IP:9981/static/tvh.js.gz:1
    onBodyResize http://TVH_IP:9981/static/tvh.js.gz:1
    onResize http://TVH_IP:9981/static/tvh.js.gz:1
    setSize http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    runLayout http://TVH_IP:9981/static/tvh.js.gz:1
    onResize http://TVH_IP:9981/static/tvh.js.gz:1
    fire http://TVH_IP:9981/static/tvh.js.gz:1
    fireEvent http://TVH_IP:9981/static/tvh.js.gz:1
    onBodyResize http://TVH_IP:9981/static/tvh.js.gz:1
    onResize http://TVH_IP:9981/static/tvh.js.gz:1
    setSize http://TVH_IP:9981/static/tvh.js.gz:1
    setItemSize http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    doLayout http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    render http://TVH_IP:9981/static/tvh.js.gz:1
    show http://TVH_IP:9981/static/tvh.js.gz:1
    success http://TVH_IP:9981/static/tvh.js.gz:702
    success http://TVH_IP:9981/static/tvh.js.gz:1519
    handleResponse http://TVH_IP:9981/static/tvh.js.gz:1
    f http://TVH_IP:9981/static/tvh.js.gz:1
    m http://TVH_IP:9981/static/tvh.js.gz:1
    createCallback http://TVH_IP:9981/static/tvh.js.gz:1
    (Async: setInterval handler)
    n http://TVH_IP:9981/static/tvh.js.gz:1
    i http://TVH_IP:9981/static/tvh.js.gz:1
    request http://TVH_IP:9981/static/tvh.js.gz:1
    request http://TVH_IP:9981/static/tvh.js.gz:1
    Ajax http://TVH_IP:9981/static/tvh.js.gz:1522
    dodirect http://TVH_IP:9981/static/tvh.js.gz:699
    createwin http://TVH_IP:9981/static/tvh.js.gz:709
    idnode_create http://TVH_IP:9981/static/tvh.js.gz:710
    handler http://TVH_IP:9981/static/tvh.js.gz:738
    onClick http://TVH_IP:9981/static/tvh.js.gz:1
    I http://TVH_IP:9981/static/tvh.js.gz:1
    (Async: EventListener.handleEvent)
    F http://TVH_IP:9981/static/tvh.js.gz:1
    addListener http://TVH_IP:9981/static/tvh.js.gz:1
    m http://TVH_IP:9981/static/tvh.js.gz:1
    h http://TVH_IP:9981/static/tvh.js.gz:1
    addListener http://TVH_IP:9981/static/tvh.js.gz:1
    addListener http://TVH_IP:9981/static/tvh.js.gz:1
    mon http://TVH_IP:9981/static/tvh.js.gz:1
    initButtonEl http://TVH_IP:9981/static/tvh.js.gz:1
    onRender http://TVH_IP:9981/static/tvh.js.gz:1
    render http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    doLayout http://TVH_IP:9981/static/tvh.js.gz:1
    initEvents http://TVH_IP:9981/static/tvh.js.gz:1
    each http://TVH_IP:9981/static/tvh.js.gz:1
    initEvents http://TVH_IP:9981/static/tvh.js.gz:1
    initEvents http://TVH_IP:9981/static/tvh.js.gz:1
    initEvents http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    afterRender http://TVH_IP:9981/static/tvh.js.gz:1
    render http://TVH_IP:9981/static/tvh.js.gz:1
    renderItem http://TVH_IP:9981/static/tvh.js.gz:1
    renderAll http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    onLayout http://TVH_IP:9981/static/tvh.js.gz:1
    layout http://TVH_IP:9981/static/tvh.js.gz:1
    doLayout http://TVH_IP:9981/static/tvh.js.gz:1
    build http://TVH_IP:9981/static/tvh.js.gz:764
    success http://TVH_IP:9981/static/tvh.js.gz:768
    success http://TVH_IP:9981/static/tvh.js.gz:1519
It works fine in FF130.0.1 64-bit on Linux
It works fine in Edge.
I plan to dig a little deeper and see what I can find.  I'm guessing that FireFox has changed something in JavaScript in a recent release because it works in v130 but not v 134.