Google Workspace Personal/Workspace Split Didn't Happen – Any Advice?

I've setup a few dozen clients with Google Workspace. Typically if you move email to Google and the customer already has a "free" Google account using their branded email, Google will "split" the account into two: Personal and Workspace

This for some reason didn't happen, and now my client has lost access to the accounts they managed with the "personal" version of their branded email.

Any advice? Workspace support didn't help much and sent me to other support departments for specific products. However this is a Workspace issue.