Microsoft Bookings - Staff Admin Role - Guest Only

septog Mayer 

I had the exact same issue.

I finally found a solution: when you begin to type the name of the user you want to add, instead of clicking on the name, FIRST YOU CLICK ON "Search Directory", AND THEN ONLY you click on the name.
In my case, doing that I was able to add a user as an admin, whereas if I don't click on "Search Directory" first, then I can add the user, but only as guest.