Corrupted Lightroom Catalog: saw message stating it needed to download the catalog from Onedrive....

When I opened Lightroom a couple weeks ago, I saw a mesage pop up briefly stating that the Lightroom Catalog needed to be downloaded from Onedrive, displaying a download status bar that showed about 50% I believe.

I did not know that my catalog was being stored on Onedrive, and that the copy from my computer was being removed.

I have not been able to open the catalog, nor find the catalog anywhere.  It was a rather large catalog at that point, containing eight months+ of work and tens of thousands of photographs, and would have been a few tens or even hundreds of gigabytes.

Some questions:

1. Might anyone else have seen this issue or something similar? What did you do to resolve it?

2. Is it a known issue?

3. Is it recommended that one use Onedrive to back up the Lightroom Catalog?

4. What might be the best way to find or restore the Lightroom Catalog?  Is it possible that it was corupted both at Onedrive and on my computer?

Thank you!