FCP does nothing when I try to share to file or anything else.

It just sits there. Nothing in the background activities cmd-9.
No error message or complaints.
It's like I never tried the export.
What can I try?
I've quit and relaunched.
My movie is long, almost 2 hours.
Maybe I'm low on storage on my boot drive, but wouldn't it complain? And I don't get a chance to change the destination drive.

Nothing happens unless you select something. Highlight a project or timeline and that should do it.
.

I have selected the project and I have selected the timeline and I still get nothing. No action no complaints. Puzzling.

I get the share menu, but nothing happens after I click on a destination.

OK, the problem seems to have been lack of disk space.
I mounted an erased 2TB solid state drive with a new FCP library on it, and presto, a short test project works as it should.
It's puzzling why it didn't give me any clues as to the cause of my problem, and just quietly did nothing that I recognized as a symptom to be responded to.
Thanks for your suggestions!