Thats pretty much it. I moved repeater field from one group to another and then dicsovered that subfields were not transfered.
Edit: After more testing i get following picture. Seems like it depends on order of your actions.
If (after repeater field got moved) i save the field group it was moved from then repeater in target group will appear empty. However if i first go to target group (without saving source group) and save it then all subfiled of repeater will be in their place. However if i try to add data i will see that repeater subfileds got rendered twice. Going back to source group and re-saving it solves the problem.