Hi @Glenn Maxwell
Could you please tell me:
Did the two users also encounter the same problem on the web client?
Are these two users users within the organization or guest or external users?
If the issue only occurs on the desktop client, ask both users to try clearing the cache or to see if Teams is not updated to the latest version.
b.Check for update:
As an alternative solution, you could create a group chat with you and the two users and then you log out of that group chat, which would create an alternate 1v1 chat for the two users.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.