Thanks. But I am back. Same issue.
Here is what I did. Switched to 2014 theme (though 99% sure there are no fields or field groups defined as php). Disabled all plugins except acf and acf-repeater.
Now I did this as network admin, and network activated acf pro. I got the prompt for the db upgrade. There are 2 sites on the network, I selected each, and the “upgrade” seemed to go fine for each. But I still have the field multiplication issue. ???