As part of Lesson 1 / Course Introduction, I created a new development sandbox. I can see the sandbox listed when I browse in the Sandboxes tab, and the sandbox status shows as Active. However, when I try to select it from the environment drop-down (top left in AEP), the sandbox is not listed. I have refreshed the AEP site several times, and the sandbox was created over four days ago, so if it is a lag issue, it seems like it should have resolved by now. Am I missing some level of permissions to fully create a sandbox?