I suddenly can't export audio

I imported an MP3 of a phone interview into Audacity to run noise reduction on it, which I’ve done several times before. The audio sounds much better after NR, but now I can’t export it. When I go to File > Export > Export selected audio, nothing happens. Same with Export MP3 and Export audio. Any idea what’s going on? This has always worked for me before.

Audacity 2.4.1 on Mac OS Catalina 10.15.6. Thank you.

More data: when I try to save the file (so I can quit Audacity and restart it), I get an error warning: “‘Save Project’ is for an Audacity project, not an audio file. For an audio file that will open in other apps, use ‘Export.’” I’ve never seen this before and don’t understand how the file is NOT an Audacity project.

I’d recommend updating to Audacity 2.4.2 at your earliest convenience as it has some important bug fixes: Audacity ® | Download for Mac OS

The message “‘Save Project’ is for an Audacity project, not an audio file” is not an error message, it is just information.
When you “Save”, it creates an “Audacity Project”. Audacity Projects are not audio files and cannot be opened is any program other than Audacity.

When you “Export” the audio, Audacity creates a normal audio file.
If you want a WAV file, use “File menu > Export > Export as WAV”
If you want an MP3 file, use “File menu > Export > Export as MP3”

Thanks for your reply, Steve.

I ended up quitting Audacity and re-importing the MP3, then ran Noise Reduction and was able to successfully Export Saved Audio.

I’m also upgrading to 2.4.2.