It might be worth experimenting with a few changes to it and seeing if there’s something specific. Spaces in and after the password have been an issue too.
Yes it will once you switch. I was originally developing under my personal account but once Liftoff! started taking off I moved to a dedicated account, which meant we had to create a new app for TestFlight. If it says 0.10.xxx in TestFlight, you’re fine though.