This may be a bug, I'm not sure. I don't recall it functioning like this in the past, however it's been over a year since I was using MP3Tag regularly due to illness, moving, and other factors. I did however use this regularly before and I don't recall this issue.
Replace with Regex seems to be working imperfectly in this case.
Steps to reproduce:
Title Tag (Example) is AAA BBB just for a general Idea of what the end result is.
Actions Quick - Replace with Regex
Regular Expression: (.*)
Replace Matches with: ZZZ - $1
Notes Regarding Above:
Field: I have used Title/Album/Artist (any will work)
Regular Expression: Meant to Capture All (I have used a few variations of this including (.*+) ... (.+) DOES work, so by capturing all (greedy) something's causing this to malfunction I assume
Replace Matches with: This is just an example, anything I try and put at the front causes this issue
Expected results is to:
"ZZZ - AAA BBB"
"ZZZ - AAA BBBZZZ - "
As mentioned above, I know that (.+) works fine and comes to the expected result. Also, I understand that formatting the tag is an options too, I have used both, but as far as I'm aware this is a bug, and though I've been using the other options the last week or two, I thought I'd get around to reporting it since I'm going to post another question anyway.