[p750mmx]

okay that is strange. For me the final version with KODI 18.6 is only working with transcoding everything to AC3, while netflix works with DD+. Just wanted to know if it would be worth to downgrade to beta 1.  

I started from scratch with the beta1, did a clean install with that. Skipped beta 2 & 3 and went directly to the Final build 2604 when the OTA update came available. I've tested quite some media after that update and the codecs that are supported are working. Maybe it's a Android audio system setting that isn't OK on your side?    

sound output: always
and then i ticked all codecs which are compatible with my receiver.

Also tried auto but this is worse for me. Which settings do you use?   

Under Android settings;
- Audio = Auto
- DTS = 0

Under Kodi: pass through = active, and then all is ticked what is available to tick

I again just tested the video/audio samples I have for audio. Every audio HD stream is played as;

DTS (+ New) < receiver info (source is DTS-HD, Atmos, and other DTS formats)
DD and DD+ (source = DD or DD+)

That is way less then when I use a Intel Based HTPC (signature), but it plays what is says it could play, so...

Connection = HDMI