This may be a dead end, but I think it would help if you showed us a series of screen captures so we can see what you are seeing. Please use the "Insert Photos" icon to include your screen captures in your reply.

Adobe technicians fixed this for me via 2 remote sessions of more than 3 hrs each. They actuall fixed it twice but after a computer restart the issue was back.
I think the issue was a tad different to what we all thought. My import window was wider than my screen so the right panel was truncated (and I'm not alone with this. It appears to be an issue in 6 languages including German but not English, you can google it). As a result I didn't see the import button. Left with a choice between <ready> and <cancel> I clicked on <ready>. Apaprently this simply ends the import process without importing anything (not sure I understand what that button is good for, my imports always end automatically once the pictures are imported). But by clicking <ready> I didn't even trigger an import. Go figure: LrC did as told and didn't import anything.
The wizards from Adobe have reset everything and re-installed everything from scratch which fixed the import window width issue, the import button is now there and the import works. But they tried so many thing, maybe there was sthg else that they fixed in this painful process.