Hi,
Welcome to Microsoft Q&A community forum!
for issues related to the Learn Profile, Certifications, and Exams, please visit the Microsoft Certification support forums:
https://trainingsupport.microsoft.com/en-us/mcp
However, if you have this problem you can do the lab by opening another page in your browser on the local PC, and use the lab credentials to access the Azure portal, and do the lab in the new browser window, then you finish it on the vm.
Hope this helps
Cheers
Luca
Please "Accept as Answer" and Upvote if the answer provided is useful, so that you can help others in the community looking for remediation for similar issues