Cranker: That's the problem I seemed to have. Skipping, Dropping. Too bad I didn't notice the 10s... Someone else did.
sch: maybe, some setups work well interchanging parts like that. Certainly didn't work with the Ultegra 8000 11sp set.
In any case, you would think that something simple like putting on the right speed chain would be elementary, and you wouldn't have to check for that. I did the next time they serviced it, but by then, it's too late.