Support helped me to resolve this.
Apparently, when I switched from trial to pay-as-you-go, it didn't take even though it was already showing as pay-as-you-go in the web interface. As a result my subscription only allowed a very limited selection of VM SKUs, just like it is in trial. Support manually upgraded my subscription to pay-as-you-go.
As for the current state of trial subscriptions, I was told that due to high demand, and referring to the March 21 statement on the global health pandemic, at this moment all non paying subscriptions are blocked from virtually all VM SKUs in all regions.