[KiCkz]

Thanks to this thread:https://forums.plex.tv/discussion/278309/grey-bars-in-hdr-instead-of-black/p2

I can confirm that kodi-20180120-67c3ce04-master-armeabi-v7a.apk is correctly showing black bars with hdr10 mkvs. All following nightlys have the grey bars problem as stated by someone else in the link.

Maybe it helps you finding the problem if you even bother...