File with removed tag showing up in Finder
I have not found a stable way in the finder to apply tags. Usually any new method I try works for the first 5 files, and then the problems arise. Even the Get Info window will not reliably work (the tags appear to be fixed, but if you close the Get Info window and open it again, none of the changes have been kept).

However, recently I have been applying tags through an application's Save dialog box. Often this works to add or remove tags when the Finder doesn't. Maybe that will work for this problem file.