LE is LibreELEC, which is the continuation on OpenELEC (OE). OpenELEC is not really maintained/developed any longer, and most of the developers who were working on it have moved on to the LibreELEC project.
With LibreELEC, if Tvheadend started up before the system had internet access then there was a problem with Tvheadend binding to any network interface, and it became unreadable. (I may be misremembering the exact details, but I believe this is close enough.) Perhaps your situation is related.
Since the OpenELEC developers have changed Tvheadend's and settings as part of their system, I suggest you ask in their support forums as the issue is most likely related to something with OpenELEC specifically rather than Tvheadend.