error 3001

How and where are you deleting this meeting? That error usually means that meeting does not exist. So it sounds like the meeting was in a calendar but not active on the Zoom app or your meeting list in your account.  

How old were the meeting IDs? If the user was re-using a scheduled meeting ID it might of expired (they expire after 30 days of none use). Or if it was a recurring meeting those can expire after 365 days. 

I met same issue when I deleted meeting in outlook calendar. the meeting invitation has been always showed in my outlook draft box. I deleted it several times, but it always appeared in draft box in 1 minutes later. I'm going crazy...