Im using the new DPS signing tool for the first time and I continue to receive the error message:
"Error Signing the App: Missing the team identifier prefix"
Any guidance would be greeting appreciated.
The App ID's prefix used in the certificate needs to match the one you have in your mobile provisioning profile, maybe they are different, see if that helps: Technical Q&A QA1879: Resolving App ID Prefix Mismatching
If unsure, just generate a new App ID and go through the process in the Apple developer portal again to make sure you have the correct certificates and provisioning profiles on your machine.