Has anyone ever seen a situation where when viewing a set of Version Changes in the Differences Pane, a non-inserted feature is missing a common ancestor?

We're using Enterprise 11.3 and Pro 3.5.5 with a published feature service sourced to a branch versioned SQL database.
This is throwing off our approvers because even though this particular editor didn't create this feature in this version, due to the lack of a common ancestor, Pro is highlighting every field as a difference. Which means they can't tell what the editor was attempting to update on the feature and determine whether it should or shouldn't have been deleted in default.
Is this expected behavior from Pro? Is there a valid scenario where a non-inserted feature in a branch version wouldn't have a common ancestor with default?