I have a CD with a track hidden in the pregap area. I extracted that tracked and saved it in the directory with all other tracks. Since I did not want to renumber all the other tracks, I chose 0 as the number of the new track.
Mp3Tag reports "write failure" when 0 is selected as the track number. The error disappears when I choose another number. I was able to save the information by retrying the operation a few times. But the error is always displayed.