Well, I wish that was the end of my troubles but it is not.
I did as you asked, and as a trial, I attempted to bake just one object before importing all the others. It worked, I then imported the others but then the exact same problem came back!! It’s driving me nuts 🙁
Can you take a look at the new file?
https://drive.google.com/open?id=1gtnIM0mgTnzDt1jDLPnND158wFKVeY0m