Yes, you are going mad, as evidenced by the fact you consciously chose to be a video editor. It happens to us all.
As for your issue, I’ve never seen FCPX do this before. Be sure you have the correct Project selected. Make extra sure.
I’d recommend the following.
Turn off background rendering in Settings.
Delete all render files for that library (via File menu).
Reboot Mac, relaunch FCPX holding Opt+Cmd to delete prefs (yes, again).
If that doesn’t work, just out of curiosity, go to Movies folder, to FCP Backups folder, open on of those backups to see if the same issue persists.
If so, move FCPX from Applications folder to Trash.
In App Store reinstall FCPX.
If you still have issues, the Project or Library may be corrupt. Need to open an older backup.