I am running v. 3.00 on a Windows 10 Pro machine (with all updates installed).
When I start MP3Tag, the program does not appear anywhere on my screen. When I attempt to run it again, same result: Nothing.
When I check the task manager MP3Tag does NOT show as a running App, but I do see in the Background Processes, one instance of MP3Tag for each time I tried running the app.
Sometimes a reboot of my system helps; other times, not.
UPDATE: After approximately 7 minutes (while I was typing this bug report), MP3Tag finally showed up on my screen. This has happened before, i.e., where it takes literally 5-10 minutes to appear on my screen.
The issue is not that I left it in a huge folder. For example in this case, it came up with the last folder I was working on it which had 14 files.