Thanks for the suggestions on things to check.
Yes, all filters off. I can view the files in Explorer. My C1Pro7 catalog was referencing images where they were stored. It took over 3 hours to convert the 7 catalog to 8, which seemed excessive. I could see some thumbnails of some images, other image boxes were blank, but the file name info was not showing on any of htem. Clicking on them did nothing, no image in the main view window, unable to edit anything.
Anyway, I deleted the "converted" catalog, removed C1Pro8, reinstalled it, re-converted the C1Pro7 catalog and now it seems to be working OK. The conversion to 8 took a lot less time though I didn't track it, maybe 45 minutes? (11,000 images)