Hi @SeaDude ,
For your first ask, DeploymentNotFound
really doesn't have anything to do with the resources being deployed per se. If you already had the resources created and you're deploying your artifacts, that's more than likely why you got Everything Ok from diagnostics. It really depends on how you were you deploying; CI/CD, VS/Code, FTP, etc. There could've been a transient error at time of deployment resulting in the received error message.
Per your first edit, this normally occurs when too many resources have been procured in subscription in a short period of time. That platform will throttle down the subscription for that region to ensure a bad actor isn't requesting a lot of resources at once.
I don't know if you have any deployment logs with the failures in it, but I hypothesize that the continued failed deployments may have triggered the throttled state. If it occurs again, you can create a support request asking for an increase in your quota.