On iOS 12.1.3 (and earlier versions), when adding an exercise from the exercise database to an open workout, the muscle group doesn’t get assigned to the exercise. It’s not a big deal, just a little annoying to have to go back into the workout to assign a muscle group to an exercise that should have a muscle group already assigned in the database.
Assigned muscle groups for exercises
Yep, that’s a bug which we’ll fix. Not a big thing but too much work selecting the group every time you add a exercise…