Hi Vincent,
The workaround below does work for "Describe core architectural components". The idea is, you activate sandbox in different module in a new browser tab, and then complete the exercise instructions for units 4 and 7 in this tab (instead of the original tab). I've used this technique multiple times and it has worked successfully each time. See screenshot below from 3 days ago for unit 7:
You can workaround the issue by opening up a new tab and activating sandbox using below link:
Once you have successfully completed the puzzle, accepted permissions, etc., and sandbox is activated, complete the tasks as described in Exercise - Explore the Learn sandbox. Additionally, you may leave the tab open and use the same sandbox for the Exercise - Create an Azure resource later in same module.
Please click Accept Answer and upvote if the above was helpful. If something is unclear or you need additional assistance please add a comment below.
Thanks.
-TP