Hi
I have same issue here
Error:
The operation couldn't be performed because object 'dc23c4f8-8e5d-41ca-b343-9a5bfa02c827' couldn't be found on 'DB3PR04A001DC02.EURPR04A001.prod.outlook.com'.
the user has been synchronised with office365
after looking into it, and checking mailboxes in the office365 (powershell), only some accounts are listed.
Any ideas please ?