Track numbers won't save

Hello, I love MP3tag and have used it a long time, but have recently come across a problem with the track field. I try to auto-number, and still see the track fields blank. When I do it manually still the track numbers won't save. I am using the latest version 2.42f, and would love some help. Thankyou!

Which settings do you use at Options > Tags > Mpeg?