Kenneth Fisher is back in the fight:
I recently had to copy an Azure SQL database (SQL db) from one subscription to an Azure SQL Server instance in another subscription. All of the help I found suggested going to the database and hitting the COPY option. Unfortunately, when I did, I ran into a problem.
Read on for the issue, as well as one way to fix it. The route Kenneth landed on was the same one I ended up going with when I had a similar problem and very limited access to SQL DB on both subscriptions.