I would like some help implementing redwing's idea.
The problem I've run into is that I don't see how to to copy all Love/Ban flags I've already made INTO my new custom "L/B tag".
1. Using Tools > Tagging Tools > Advanced Search and Replace looks like it might work (with Tag 1 = "Love", Tag 2 = "L/B tag"), but it doesn't. Nothing happens after doing running this search and replace, the files are completely unmodified. I imagine this is because custom tags are basically strings to the program, but the internal Love tag is some binary data inside the musicbee database, so the program won't take any action.
2. The other option is to use the "sort by this column" feature. Since this groups together files with the same love/ban status, it is reasonable to highlight all of them and write the "L" or "B" to the tag manually. The problem though is getting all your files to display in one place.
For single playlists, this is fine. But for a folder of playlists this doesn't work. On the left hand side of MusicBee I have two playlist folders, each containing numerous playlists. If I select one such folder, then the right hand side of MusicBee will display all files inside all the contained playlists EXCEPT those files that are "banned". This last point is unique to playlist folders, it doesn't happen with single playlists.
Any ideas? I don't want to go through my playlists one by one. Also, I can't simply select the "Library > Music" folder on the left hand side of MusicBee, because this is mostly empty (my playlists contain songs that aren't inside the MusicBee Library folder).