I was having the same issue because I am using cloned field groups quite heavily. But I discovered a work around.
1. Set the Collapsed field value in the Repeater to your cloned field.
2. In your cloned field group add the class “-collapsed-target” to the field you want to show when the repeater is collapsed.
3. Enjoy.
Also, if you have multiple fields per row, one (or more) of which you want to display when the repeater is collapsed, add the “-collapsed-target” class to ALL the fields you want displayed. Just make sure they don’t add up to more than 100% width. I do this with a Person repeater where I show the First Name and Last Name when the repeater is collapsed.
This is definitely a hack, but for now it works.
