It will not let me select a mission or to the ambassadorbank or anything

I've also had this issue but without the GamerTag change. I think there may ne different password and GT length limits on 360 vs Modern though

My mate had the same problem, I have also just encountered a problem after I completed the first two missions on Vet it only gave me the complete the mission on any difficulty but not the vet difficulty achievement. It won't even let me select mission select
for some reason as well.

don't use mission select. use continue campaign.

.

mission select lets you play that one mission then takes you back to the menu.

Never mind I figured it out all I had to do was unplug the xbox😅

Hi, I hope you're doing great out there. I am an Independent advisor and I am here to help you with your concern.

Kindly perform a powercycle on your controller by following the steps below:

"1. Press and hold the Xbox button for 5-10 seconds, until the controller turns off.

2. Wait a few seconds, then press and hold the Xbox button again to turn the controller back on."

For your reference, you can check this link: https://support.xbox.com/en-US/help/hardware-ne...