Ah, I see what you mean. When you review a submission, it uses the update function at the bottom of your screenshot (because it's only changing submission metadata, not the actual submission data.) I think line 165 is wrong and should have this instead:
instanceId: submission.instanceId
submission.def doesn't seem to have instanceId filled in at that point. This never worked for you, right?
We'll get this fixed in Central. One things to note, though: Keeping the schema of the audit details consistent and up to date is tricky for us, so I would try not to rely on it. It looks like this piece was never really tested.