One album of flac files won't tag correctly for Windows Explorer

[ohrenkino]

@Ven101

Well, did anyone at mp3tag ever get to the bottom of this?

The root cause is the bad implementation to read flac tags on Microsoft's side. There are some plugins around that overcome this flaw.
see e.g here:

Issue with cover art writing to mp3 files but not to flac files in 3.20

If your issue is that cover images are not being written to FLAC files, then when you reload those same FLAC files into Mp3 tag, their covers should be missing. Are they in fact missing? If not, that means the covers are being written to your FLAC files by Mp3tag but Explorer is simply not showing them. That is a whole different kettle of fish, as they say. Your MP3 vs FLAC icon display issue may reflect a difference in your Explorer View settings for the parent folders for each type. Try …