With the latest version 3.4.1, I have problems saving MP3 exported files. I’ve tried all types of settings with no luck. It’s saves the MP3 correctly 80% of the time, but 20% of the time it just saves a “file.” It seems it’s not creating the file extension.
I’ve exported the exact same over and over, even with the same filename, and sometimes it saves correctly and other times it doesn’t. Just random. Never had a problem before the latest version update.
Do you have both versions installed on your machine ? Please uninstall 3.4.0, then verify that this is still occurring. Double-check Help > About Audacity that it says 3.4.1.