Here's a little tidbit that may save some of you a lot of wasted time (I learned this the hard way):
If you ever need to change the binding of fields and sections for whatever reason (due to sections breaking, data connection changes, field name changes, re-arranging sections, etc.), then be certain to re-bind your sections outside-in, and fields always last.
For example: say you have a repeating section with 100 fields, and that repeating section lies inside a collapsible normal section. For whatever reason you need to re-bind everything to your data fields and folder structure. If you had tried to re-bind the 100 fields first, to your own horror you would have lost every single one of those bindings upon binding the repeating section or outer section they are contained in afterwards, and you would have had to start over by binding all 100 fields again.
The lesson is, bind from outside-in, meaning the top level outermost sections first, then sub-sections inside that, etc. until you have the fields remaining, then bind those. This will save you a great deal of frustration.