OK, but before you give up, as steve said for FLAC files, the encoding is: L, R, C, LFE, SL, SR, RL, RR
So to keep things simple, go to your 7th (2nd to last track), and in the drop-down click on Make Stereo Track.
Repeat for the 5th track.
Repeat for the 1st track.
Make sure you start at the end.
Merry Christmas.