See the following comment on reddit:
https://www.reddit.com/r/AZURE/comments/1dgefmd/comment/l8ufwik/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button
It would appear that for some reason, MySQL is not available at all on the regions I tried to deploy to. But then why does the Azure portal allow me to select those regions and submit the deployment in the first place? The form should not give me the option to deploy to regions that have no SKUs available in the first place. And the error message should reflect the actual problem, rather than reflecting nothing specific at all.