I have a problem with mp3tag 2.85 and Windows 10 FCU x64.
I can see missing informations in mp3tag (track number, year etc).
For exemple the album (flac files) year i can read in Tagscanner or dbpoweramp tag tools is 207-10-13 and if I watch in mp3tag 2.85 there is nothing. I have same problem with track number and cd number.
Regarding FLAC files you do not need to configure "Ape, Mpc ...", do not touch it.
See dialog "Mp3tag Options/Tags", "Restrict incoming files to:", there is a list of file extensions, which Mp3tag will load.
Make sure to have there also an entry with the filemask: *.flac;
Make sure that the "View/Filter" [F3] is not active.
Attached is a zip package, having one flac test file, Mp3tag can load it. test.flac.zip (370 Bytes)