Step 'Ignored' property only set when not ignored

I chased down an issue today that I suspect may be a recently introduced change or bug. I have an Update step and I response map the ignored property to 'fulfillment_already_exists' for later evaluation in a Branch.  Today the flow was reported with an error and it turns out the cause was a missing 'fulfillment_already_exists' property on the record. The Branch had a condition:

fulfillment_already_exists is false

But because the 'fulfillment_already_exists' property didn't exist, the Branch resolved to no action.

This seems like a bug. Whether it's ignored or not, the ignored property should be set and available to the response mapping. I know the response mapping is executing when the Update is ignored because the fulfillment_already_exists property is present with a true value, likewise when the Update is not ignored the id is mapped.

The integration in question rarely (once a week?) sees data that would run through this line of the flow, so I can't say when exactly this issue started. But this was working a couple weeks ago, so it seems something changed.