So think I figured out cause. Compact mode. Try turning compact mode off, closing app, and then trying. Worked for me.

I prefer compact mode though so I hope they fix it.

EDIT: I also got to it to work by clicking post then clicking image and sharing rather than clicking the post directly from feed. Odd.

iPhone 12 Pro on iOS 16 here. TestFlight latest version. Memmy has full access to my photos in privacy settings.

You?