Why Teams Sometimes Won’t Allow External Users In

[TonyRedmond]

Teams supports external access through guest account membership in teams and external sharing of shared channels. Sometimes, things go wrong and sharing can’t happen. In this article, we explore some common reasons and explain the solutions. And the need for patience!

https://office365itpros.com/2022/05/26/teams-blocks-external-users/

[#2]

for me, the keyword in the article is MS message is "not useful"/ "not helpful"~~~~
but article itself is helpful

indeed we take a lot of time to explain to user it's not our problem,
even worse is sometimes I need to find out if it caused by us

the ACL need to be better
I have to say at least it has a failed message, some failure in Teams is by design and no warning