Up until the latest release (2.27) I have been able to use square brackets in the Tag->Filename function or mp3tag successfully. I have a naming convention i use (%track%. %title% - [ %artist% ].mp3) for all my mp3's and wish to continue this practice (10,000+ mp3s)
I assume this is a bug if not, is there a way i can continue to do this?
If you put backticks around the square brackets, it should work.
%track%. %title% - '[' %artist% ']'
Edit: This is also explained inside the help file and the What's new? document which popped up after installing MP3Tag 2.27.
nice work. Works a treat. Any reason why this changed?
This change is part of the new parser. I guess Florian can go into the details if you want.
I had to rewrite the whole parser, because the old one has major issues with backslashes and double quotes. One new feature of the new parser (which behaves almost like foobar2000's TAGZ) is the conditional nature of the square brackets. I like it 
Best regards,
~ Florian
No doubt about it, you rock !!!