oh my word looking at your image may have just triggered a realization for me for how to solve this. Rocks won't move onto flags. I think I can push it out. But I need to push it out onto an exact block to reach it.
Oh, yes, thank you! That was the trick. That one was driving me crazy. I *almost* saw what you did. I wondered about putting a rock there, but my brain was stuck on trying to get the rock onto where the flag is to prevent the cat getting ejected. I forgot I could push the star.