External Guest User- Error

An external user was added to a team and a private channel while he's able to see our organization when he tries to select it he get an error message saying he does not have access to our organization. Using Teams in his own organization works just fine the issue is when switching to ours as a Guest.

We removed and re-added him hoping it would be a fix but it was not. When we re-added him he is showing up in the list of members but he does not come up when you search for his name in the members. Thinking this was another issue we tried to remove him again this time we got an error message saying "This member is the last owner on a private channel and cannot be removed" Correct me if I'm wrong but external guests cannot be owners of channels in our organization. There is also 2 other owners in the private channel he is not the last owner.

Has anyone seen this issue and do you have any recommendations?

Our external guest setting is turned on as we have many more external vendors in our team.