I've been creating additional tags in my flac files to further identify my music to SlimServer. The ones I've recently created are DISC, DISCC, and COMPILATION.
After manually populating these 3 tags with Mp3tag v2.36c, I wanted to list which of my flacs didn't have one of these tags filled in. Normally, instead of writing an action, I just use the filter dialog at the bottom of Mp3tag. When I clicked on Field to select one of the new tags, I noticed that COMPILATION was not in the tag list. However, DISC and DISCC were both there. I looked in usrfields.ini, and COMPILATION was defined there, so I'm at a loss to explain why DISC and DISCC were listed, but COMPILATION wasn't.
Do I have a bad setting somewhere? Is it possibly a program bug? Or user error (most probably)?