Additional meeting and call-related features and issues within Microsoft Teams for business
I also seem to being having this problems with "Guests" outside the company can not see the PPT's when shared. I wonder if the issue is a permission thing? Either way, this problem seems the same in my situation. The workaround has been to share the screen rather than the PPT. If you have sound/video click the system sound check box! I hope this is fixed, or the error message is improved.