Key problem: the "Parent" field in ADO can contain only one value.
In ADO, a feature is automatically associated to the same theme as its' parent epic, but in Aha! this is not the case.
So when features import, we associate them with the correct parent epic, but NOT the same release as the epic is associated with. Instead, they go into the leftmost active release and must be manually moved.
Having new features created via an ADO integration assigned to the parent epic release by default would solve this.