One star Iron Man stuck on 3/5/5

I’d been wondering why I had such a huge surplus of IM35 Yellow but I hadn’t really been paying attention as I was burning my 1* covers for XP. It seems my Iron Man is trapped at 3/5/5. When I try to add a red cover, it does not let me choose to reduce blue or yellow, it just flashes the red 3 screen (as if I had just added the thirteenth cover) and keeps on being 3/5/5.

My other 1* characters work as they are supposed to. It’s only Iron Man that doesn’t want me to adjust his powers.

Did some more experiments. By selecting IM35, going to his red power page, and adding the cover from the button there, I was able to decrease yellow and get him off 3/5/5. The error appears to be tied to the train button on the “claim your rewards” page. I’ll try some other things when I have more red covers to see if this is reproducible. Not that anyone cares.