It also seems like HANDBRAKE is putting some extra bytes in some of the tags or miscomputing some data lengths within the file, thus making it unreadable to MP3Tag. I opened the file using MediaInfo to see where the problem was occurring since all of my video players had no issues with the questionable files. MediaInfo showed conformance errors (formatting errors violating the tag standard). All of the files used HANDBRAKE. I did a cursory search and it seems HANDBRAKE had introduced some bugs in one of its versions.
Thank you very much for the heads up!
A free alternative to Handbrake is the Windows app FFMPEG Batch Converter AV Portable
I have used this without problems, although not often enough for me to give it an unqualified recomendation. But the Windows interface looks great and is easy to use.
You may have to look up the needed FFMPEG parameters if the supplied presets (there are many) don't apply to your conversion.
I've been using Wondershare Uniconverter for years. They seem to run the fastest and handle every format I can throw at it plus it'll fix errors in the files.