Waiting room suddenly not working

I don't know if this is a personal account or business, but in case it is not personal, Can you check if the admin by any chance enabled the Waiting Room Option "Users who are not in your account and not part of your whitelisted domains"  and the users bypassing the Waiting Room as coming from a whitelisted domain?

Go to your Zoom Portal:  "PERSONAL > Settings > Meeting > Security > Waiting Room > Edit Options"

While in there, check the other other available options to verify if that could be the culprit.

Let me know,

Vinnie.