Unable to export photos Lightroom


I updated to Catalina a few days ago and have had a rash of problems with Lightroom since
1. Lost all of my edits I had been working on
2. Lightroom not recognizing there are photos on Sd card
(both of these issues I've posted on already)
The latest issue ....
I uploaded the series of pics I had been previously working on and lost (had to put them on desktop first from SD card then to Lightroom) & Set my destination folder to my external hard drive, like always
I was able to edit and export the day I had originally did this. Today I was able to edit, perhaps through the smart preview option, but cannot export. It says my file is not found, despite my hard drive being plugged in. When I go to library there is no (?) beside the photograph. I'm at a loss......