My Smart Preview scheme is broken following a migration

I'll put my best guess up top:

I moved my Lr Classic (14.4) catalog from one computer to another, (MacOS) and on the new computer, my username is different - I think that broke the workflow.

I moved .lrcat and .lrdata, and the folder structure is the same on both old and new machines: Users/myname/Pictures/<a year folder, with month folders within that)

The symptoms are that:

The original photos are all on my NAS, and show up when it is connected - but doesn't indicate "Original and Smart Preview"

I still have the intact Lr catalog on the first computer, I'm willing to start again. 

Suggestions?

And I thank you for whatever you can offer.

Dan