I too have the same problem on macOS Sequoia RC. When I do it in C, it works. I wrote that parts of my app in C because of this problem; for a reason, AXObserverAddNotification() is always failing when I call it in Swift.

Any good news? My archive's direct distribution is still stuck at "In Progress".

It is done now. Thank you so much. I don't know what the problem was. If you know, that would be better to have an answer here.