Host's video no longer works on some established invitations

For several months, people have been using the same meeting link which is designated as recurring and for an unspecified time. Over the past few weeks, my video on a few of these calls has been blocked. This is not so for all calls even on the same day. Can anyone tell my why this is happening and how to fix it? I've even tried sending a new invitation link to these same people and it doesn't work. Thank you.