When editing an ampath form, the values in the repeating section are lost


We are encountering a situation where while editing an AMPATH form, we’ve lost values in the repeating sections. It seems that the form sends the repeating section as an Obs group and marks previous Obs and their children as voided. If we edit only one value in that repeating section, a new Obs group with a single value is saved. The question is, is this a bug or a feature? If it’s a bug, is it a form bug (the form should send all values in the repeating section on edit), or is it a backend issue (it must somehow deal with the old Obs group children)?