LG C9 OLED 2019 rooted no AC3 or DTS Sound



hi,
as title says: i’ve a LG C9 OLED form 2019 rooted with Kodi 21.0 connected to the AVR Yamaha RX-1080. Unfortunately it plays no AC3 or DTS. Passtrough in Kodi is activated and in the menu DD and DD+ is selected. DTS isn’t avaible in the menu. In the TV eARC and Passtrough is also activated. Iv’e already activated and deactivated the functions in Kodi and the TV but i get no sound no matter what i do. 

Dolby Digital: not working -> only working when Passthrough in Kodi is deactivated but then only in PCM 2.0
True HD: only PCM 2.0
DTS: only PCM 2.0
DTS-HD MA: only PCM 2.0

What am i doing wrong?

I also wonder if the automatic “Adjust display refresh rate” works with webOS so that movies displayed with 23,976 fps.

Thanls