Calendar error, looping "revert edit send" for Exchange account external invitations

I am having the same issue as another expired but unanswered post. If I click inside a Calendar invitation, such as to use a WebEx link [very common], I get a looping "revert, edit, send" popup that can not be closed. Calendar app must be force closed. The Exchange account dis-associated with Calendar. Calendar app launched. Calendar app re-associated with the Exchange account. Send will end the loop, but sends a similar duplicate invitation to the entire distribution list. I understand Exchange may not be playing nice. Any workaround for my end or clues for our exchange admin appreciated. -Thanks