One of my Office 365 user, suddenly missing

One of company user suddenly missing from active users, and I can't find it on Deleted user, last night my team on New Zealand doing synchronization, I can see all user with onMicrosoft.com are on deleted users including my account, but I can still see my account on active users tab, but one of my user is suddenly gone, only his onMicrosoft.com are in deleted users tab, I cannot see his original account on deleted users.