I downloaded some voice test files of various multichannel flac files. I copied them into the downloads directory on the local filesystem and used the music player. Instead of playing from the library I navigated to the downloads directory and played the files one by one.
7.1, 6.1, 5.1, stereo (2.0) all worked ok. The surround50.flac file played back FL and FR correctly. FC did not play back. RR did not play back. RL played back through the centre channel. The 3.0 file (center.flac) played back only L and R. The 4.0 file (quad.flac) played back only FL and FR.
Now, strangely enough, this was repeatable provided I started from the 2.0 file and worked upwards to 7.1. I found that if I rapidly changed from say the 7.1 file back to the 5.0 file, it worked ok and all 5 channels were located ok. Same for the 4.0 and 3.0 files. It would seem that when the player dropped back to the default 48kHz 2.0 it then couldn’t handle 5.0 / 4.0 / 3.0 files correctly. Only when it was in the 6 or 8 speaker mode that it was playing the 5 / 4 / 3 speaker files correctly.
I have noticed a similar issue when playing music files (even standard 2.0) after I have been playing movies with multichannel HD soundtracks. If you open the music library immediately after watching a movie with a DTS-MA soundtrack, then it won’t play back standard audio tracks or even the navigation sounds. You have to select a high bitrate multichannel audio and play back before it will recommence playing standard stereo FLAC files.
I attach the test files I have used: