I followed the procedure below:
1. I want to change an ID3 in a song i.e. "Artist" from Floorfilla to Stat Bun
2. I press Enter on the keyboard and the blue bar moves down to the next song
3. I click the icon of the song up, so I put the blue bar again on the song I changed to read better what I have done
4. I notice that the panel on the left isn't up to date, it contains wrong data: they are data of the song down, so if I click "Save" icon, MP3tag 2.40 writes wrong ID3.
P.S. Sorry for my horrible English.