Thanks Quinn, this is resolved now. Root cause on my side: I was firing the submissions without --wait and not keeping the session alive, so the uploads never completed cleanly — which lines up exactly with your "failed upload → sits In Progress ~10h → vanishes" explanation. Fix: I switched to xcrun notarytool submit --keychain-profile --wait, submitting the two architectures serially and letting each finish before starting the next. Both came back Accepted within a few minutes, and stapler staple + stapler validate now pass. Appreciate the help.