UPDATE: Submitted on 3rd October. Approved on 13th October Happy days, I phoned service advisor today again but they really have no control of any app submissions. They have no access and can't see it's status or even what has been submitted. Only method of contact is email via App Store connect. unfortunately I've yet to get a reply via that method. Lucky for me, that's me done. Good luck to everyone else.

Thanks for your input. That's given me some confidence that the process is still working. I should have said that the app already contains a simulation mode which uses the phones accelerometer instead of the Bluetooth device (it's an angle guage essentially). The app works the same way use with a different input. The video was made using the real device. So I really hope I've given enough info. As I said, I've already requested a status update and escalated but havent heard back. I'll see what happens Monday/Tuesday before contacting them again regarding the error message.