MS Teams: Meeting participants cannot view chat or click record

Hi MagrietdeV 

So for your plenaries and parallel sessions you were using Channel Meetings. This is where the meeting chat is actually a conversation in the associated channel. Although you gave you users guest accounts, they were perhaps not using them before joining the meeting from your pdf. To access a channel meetings chat you need to be logged in as a users with access to the channel or switched as a guest to that team. I suspect many were joining using the accounts of other organisations, so didn't have permissions to access chat unfortunately.

When you organise through Outlook there is no channel, and anyone who joins can access the meeting chat. 

I've seen events force this to work by preventing people joining meetings as external attendees through Teams policies, so they have to load Teams and either log in or switch to your tenant before joining your meetings, but I'm not sure that's a brilliant users experience.