Information missing in mp3tag

[LyricsLover]

I have done this thing called "search" for you and found:

Some files show incorrect (or no) time in Length field

There are freeware utilties around that do just such checks: mp3val mp3diags foobar2000 mp3val and mp3diags have an scan mode so that you can decide whether you want to fix files with problems. Both programs have their virtues and you probably have to use both to get rid of all faults.