.....Pretty annoying when I want to watch a movie just with a TV... Are you guys even working on the issue? An update from your side would be fine...
And as info: No, the AC3 core is not available in the MKV. But this was not a problem at all in FW 2.0.1
Not sure what your problem is?
TrueHD 7.1 passes fine via HDMI using latest firmware 2.0.5 (and Kodi 17.4 using wrapper gets same result). It has done so since the original firmware upgrade last year.
You can't pass HD audio with optical, only HDMI.
If you are trying to send TrueHD to a TV, it won't work without converting the audio to something your TV can handle.
Are you sending audio to an AVR first?