Using MP3Tag to clean-up my library and found some M4a files that MP3tag could not read or write tags for. Did a search of the forumand it looks like this may have occurred previously but with m4v video files. As an FYI, I can read / write tags in itunes v10.1. I thought maybe the tags were corruptso I tried to use ID3Killl to clear all the tags but that didn't do anything.
Also tried another editor, TagScanner v5.1, and it cannot read / write tags for the files either. So this may not be a "bug" in MP3Tag.
Anyone got any ideas?