Find the file "%APPDATA%\Mp3tag\data\columns.ini".
You can get it quickly by pressing [Winkey+R], fill the upcoming dialog field with "%APPDATA%\Mp3tag\data\columns.ini" and press 'OK'.
Afterwards Notepad should display the file.
The contents of the Inifile is divided in sections.
Look for lines beginning with the text "width=".
If there are entries with rather small values, say smaller than 5, then change the value to 20.
Afterwards save the file.
Restart Mp3tag and check if you now can see the formerly lost columns.