O365 Inbox vanished - but, but, on next log on it's there again?

[speckytecky]

I had a frantic call on my mobile - don't ask

 

from a member of staff who is away on a course complaining that on opening O365 they saw that their Inbox had vanished.

 

My immediate thought was that the folder had been inadvertently dragged and dropped by them into another folder but I wasn't able to explore at the time as I was replying having pulled into a layby.

 

A further message a while later saying that they had opened it again and all was normal again.

 

Any further thoughts on what may have happened would be welcome fellow Edugeekers.

[FN-GM]

Is there a chance they are logging into the mailbox on an another organisations computer that has office 365?

 

I have had a user who does some work at another school, they have a mailbox they don't use at that school. The other school has SSO. The tried to get into our mailbox on the other school computer computer and it automatically signed them into the other school mailbox and it was empty because they don't use it.