What is going on here?
Forensically, I think the system became confused when the Default Catalog was initially moved, and, upon not finding it, a new Default Catalog was created automatically.
I believe some of the lingering jobs (indicated in your screenshot as "some catalogs offline") must have been queued to that new, unwanted Default Catalog (which may have since been deleted.)
On the development side, we'll need to consider how to make the software more resilient in this scenario.
As to how to get things back on track, I'd recommend the following:
1. In the Catalog Status window, click the "Stop Catalog Import Tasks" and "Stop Preview Generation Tasks" buttons. The various Catalog Tasks should settle to an Idle state. (If tasks do not return to Idle, let me know, and we can try a more low-level reset.)
2. Use the "Sync Catalogsā¦" feature to continue building your catalog. In the Catalog Sync window, click the name of your catalog to edit its settings. Verify the "Folders to Include in Sync" paths look correct, or edit as needed. Enable the catalog for Sync via its checkbox in the Catalogs to Sync pane.
Select "Quick" for Sync Mode. Start the Sync.
This should resume building your catalog from where it left off.
Hope this helps,
Bill