Team member is not able to enter text in the chat room

There are 3 members in my team, I am the leader, in the recent member list, this team member who is unable to enter text in the chat room, has a colorless circle to the left of his userid, the other 2 members have a green circle. I do not see anything in the settings which would allow me to enable his ability to use the chat room. Has this issue come up before?

Noup

"has a colorless circle to the left of his userid"

-> I wonder how someone would post when they are offline.