Have you experienced anything similar?
It's a known bug with a simple solution. See
MiniLyrics broken?The synchronized lyrics are not supported by MC
Correct. But MiniLyrics does write unsynchronized lyrics as well. I haven't tested it, but I believe the problem I originally reported in
Is there a way to grab lyrics easily? was recently resolved. (To be precise, a problem was resolved—I'm just not sure it was the cause of the trouble with the MiniLyrics unsyncrhronized tags not being readable.)
While the user-contributed synchronized lyrics supplied by MiniLyrics may be the only sort of thing available for that purpose, it's definitely not the best source for unsyncrhronized lyrics. But as you seem to realize...
Is there a way to make the program run through your library and/or playing now (or a folder), and autotag them all?
...it's also important that they can be obtained in a reasonably automated way. The best solution I'm aware of is the one described
here—using a
foobar2000 plugin to get lyrics from
LyricWiki and write them to the file tags.
Although the WikiLyrics lyrics obtained this way are also user-contributed, they seem to be of a better and more consistent quality that those downloaded by MiniLyrics. For a large portion of the songs for which it has lyrics, WikiLyrics also has the "official" Gracenote lyrics. So it's also a good first place to look if the downloaded (user-contributed version) is not of the quality desired. I use MC Links to lookup what's available at WikiLyrics for that purpose.