Just a quick tip about why you might notice some sizes are not available when you are attempting to change the size/scale level of an Azure virtual machine in the portal.
I wanted to change one of my Development VMs to a DS12_v2, but that choice wasn’t available:
It didn’t immediately dawn on me why it wasn’t available, so I thought I’d try PowerShell:
Read on for the solution, as well as a few other common causes.