Still no fix... this is getting ridiculous

I'm no longer getting the rejection message/ email within 30 minutes, although it's still not appearing within appstoreconnect. So it looks like they are aware of it and maybe disabled the rejection message whilst they fix the issue?

I've submitted a ticket. By the time they get back to me, it'll probably be sorted. Ill post their reply when I get it

and me- United Kingdom

Ok, I had the same issue with my new M1 chip. A previous Xcode issue had made me open Xcode using rosetta. (get info) etc.. Anyway, it seem that this storyboard error was caused by rosetta. So opening it without rosetta resolved this for me. (original error must have been resolved in an Xcode update)