Since shortly, presumably after an automatic update, TVheadend 10.0.0.126 was installed. This lead to complete failure of TV+PVR services.
Addons.log has this error message:
Code
###############################################################################
# ... output of cat /storage/.kodi/userdata/addon_data/service.tvheadend42/service.log
# LibreELEC release: Generic.x86_64-10.0.2
#
################################################################################
/storage/.kodi/addons/service.tvheadend42/bin/tvheadend: error while loading shared libraries: libx265.so.199: cannot open shared object file: No such file or directory
It seems that a file is missing (or was deleted during the update process).
After a downgrade to TVheadend 10.0.0.125 everything worked fine again.