@louf Sorry for the late response, I am currently not maintaining Kodi packages since Kodi 19 does not support H265 HW video decoding on RPi 3/2, which are the ones that I still use for Kodi.
About your problem, I can't really tell, never happened to me and I never anyone complaining about something like that. Can you reproduce your problem and post a Kodi debug log? A photo/screenshot may also help.

@Clyde said in Subtitles error with OMX Player on Pi 4 with RetroPie 4.6:

Two more questions, does VLC have HA "just like that" or do I have to activate it somehow?

No, hardware acceleration is used by default.

And does OMX have any advantages left over VLC?

Yes, it's still faster than VLC with HW acceleration in EmulationStation.