I have heard from a few people that the 5.1 beta that is listed in the video posted here, does not seem to have the audio passthrough issues that the new 5.1.1 release has.
I haven't tried it myself yet, but I am planning on trying it. It can't be worse than what I have now.
I will post back once I have tested it with kodi 17, however it could be next weekend before I have time to do it.