Explanation
The environment doesn't show up in the drop-down menu of Power Virtual Agents Your environment might not show up in the drop-down menu due to one of the following:
The environment doesn't have a database created. To resolve this issue, go to admin.powerplatform.com to create a database in your environment.
The environment is created in an unsupported region.
Reference: https://docs.microsoft.com/en-us/power-virtual-agents/environments-first-run-experience