i've had the same error when i change them in the list and not the mask.

only thing there is i found it to be the level volume check box being checked that caused it to change to the disk 2 track one and so on.

It was my fault.

When entering <Track#>, it entered limit to two digits by default. Removed that limitation ":2" and everything works fine.

MediaMonkey 3.0.1.1127
When ripping a multi disc album I set track numbers as 101 to 120 for disc 1, 201-220 for disc 2, and so on.
When ripping that value is not passed to build the filename as "101 track1", etc.
MM uses the original 1-20 track numbers.