TVheadend and Raspberry pi5 cannot see all DVB-T channels

Had Tvheadend 4.3 working fine with Raspberry Pi4 and LibreELEC 12

Upgraded to Pi5 and cannot get Tvheadend to see all channels, it only picks up about half of them.

Also tried installing Tvheadend on vanilla Raspbian Bookworm x64 and same result

Can scan from cli using dvbv5-scan and w_scan_cpp, and they both see all channel no problem.

Using USB tuner WINTV-DualHD with recommended firmware from Hauppage

Strangely NextPVR with LibreELEC picks up all channels no problem, but would much prefer to use Tvheadend

Are there any known issues with Tvheadend and Pi5 ?

Update: seems if left for some hours and/or rebooted, Tvheadend is eventually seeing the missing channels