Issue with outlook zoom app

I am an executive recruiter and regularly schedule meetings for others to attend that I will not be involved with.  I've used the outlook zoom app for almost a year and set up over 200 meetings this way during that time.  During the last week I've had three separate clients reach out to me saying that they couldn't join the meeting and received an error code that the meeting was scheduled at a different time.  All I'm doing is adding a zoom meeting to an outlook invite.  The outlook meeting time is correct and with the way the app works I'm not setting up a specific "zoom time" so I have no idea why they would be receiving this error.  Any thoughts?