I have a similar issue on my device Phicomm-N1(not supported). The problem started since 19.5rc1 and all the later versions have the same issue. 19.4 is fine.
My device is connected throuh a Yamaha avr to the TV with hdmi connections. The phenomenon is: after playing a 5.1 channel content, there is no sound for all the 2.0 channel contents, including the UI sound effects. But it’s still ok to play other 5.1 channel contents.
Restarting the avr or the TV doesn’t work. Rstarting kodi doesn’t work either. Only rebooting my device works.
So I’m still staying at 19.4 and this is just FYI.