P365: Prepare Error Teams migration Prepare Error - unable to determine the target primary SMTP address or user principal name (B881571)

Customer had new requirement for Teams and Unified Groups, so I had P365 Directory Sync enabled, created a new project and set it up with P365 DS
Created a Read and Match Workflow for source and target in P365 DS
The new project discovered the users, teams and groups
When I try to run Prepare, I get a Prepare error

Error
PrepareStartError
Unable to prepare upn@tenant.onmicrosoft.com, unable to determine the target primary SMTP address or user principal name. [UserMigrationId #11111111]

I also noticed in the WorkFlows that the ones automatically created by the T2T setup show a state of Not Ready

Run a match from the UI first on the team to populate the new UPN info etc.

Then run the Prepare step