Training: Instruction to develop new skills.
Hi Nina,
Please Activate a new sandbox, review permissions, solve puzzle(s), etc., and then once the black cloud shell screen is there on right, open a separate tab and browse to https://shell.azure.com . If this opens successfully you can copy/paste the exercise code into this tab instead.
Please note that Unit 3 exercise and the later exercise in the same module need to be completed in the same sandbox, in sequence.
Occasionally other people have encountered same issue as you are experiencing. Hopefully above workaround will allow you to complete the exercises.
Please click Accept Answer and upvote if the above was helpful.
Thanks.
-TP