I can't get OMXPlayer to play audio over Hdmi when running a mp4

[Khiffe]

Greetings
I have an issue with my Pi4 when it comes to play audio over Hdmi when playing an mp4 file.
if I run it using the analog output after changing to local ir works properly, but when using hdmi parameter there aren't any audio.
Works: omxplayer -o local sample-mp4-file.mp4
Not working: omxplayer -o hdmi sample-mp4-file.mp4

If I run the file from VLC it works perfectly over hdmi

The Pi is fully updated today. but it didn't work befor the update either.

Does anybody have any suggestions?

Cheers
Kris