Co-organizer cannot unmute or share

For a recurring Teams meeting in which I am the organizer, one of my co-organizers was not permitted to to unmute or share during a call where I was not present. We tested the meeting later, together, and even after I joined, the co-organizer's camera, mic and share buttons remained grayed-out, and this co-organizer was listed in my People pane as an Attendee. 

Here are the Meeting Option settings I have: 

• This person is included in the 'Choose co-organizers' list
• 'Who can present' is set to 'Only organizers and co-organizers'. 
• 'Who can bypass the lobby' is set to 'People in my org, trusted orgs, and guests'. This person is in my organization (same company).

This person joined from their Outlook calendar. Does anyone have any suggestions on how to fix so that my co-organizers can conduct a meeting that I (as the organizer) cannot join? Thank you