Ditto here. It seems I can edit info on the first few sets in the list within the activity but beyond a certain entry, fails with the error noted by original poster.
Been running into the same problem. This morning I edited one at a time, then hit the back arrow. It saved them. PITA, but it worked until I tried to select “Calf Raises” - then got the error again that it could not save. I selected a different calf exercise and it saved. Odd that it will work one at a time.
I have same issue. It lets me edit & save weight and reps, but not the actual exercise name. My workaround for the time being is to edit in the web browser. That works fine and will then update the info in the app too.
