Image gen instructions only being followed after regenerating the response?

Been having an issue with ChatGPT (5.5 Instant, Thinking and older models) only following image generation-related custom instructions after I regenerate the response. It started around the time Images 2 released and during the A/B tests just before that so I'm reasonably sure it's related.

I have a couple specific instructions which are basically "after generating, provide alt text + a brief generation success review in the same turn." It's able to follow this fine but only after I regenerate the response that contains the tool call, otherwise it just calls the tool and ghosts after. Putting those instructions in the actual chat doesn't help either.

Is this something anyone's managed to fix with custom instructions/prompting or is it because of the model rerouting?

(And has anyone found a workaround that doesn't involve manually regenerating every time and wasting image gens? 💀)