23 votesWarren responded
Currently not supported but as a workaround you can remove the guest and re-invite them as full member.
Thank you for the feedback!
-WarrenMark Warpool commented
I wonder what teams considers as someone "inside my organization" versus outside of it. Are people only considered "inside my organization" if we all have Office 365 accounts created by our IT department? If that's the case, then you can't really use the 'free' version unless you're already subscribed to Office 365.
We are actively looking into getting this fixed. Stay tuned for further updates!