A Microsoft file hosting and synchronization service.
I have exactly the same problem suddenly. Family 365 account and up until today, a common shared folder has been appearing in all other OneDrive accounts with everyone able to edit files within File Explorer. I changed the alias of one account last night and suddenly the Shared folder doesn't work and appears with the computer name appended. The link is broken and nothing I do can bring it back, other than a USELESS url to the web version.
When are Microsoft going to sit up and take notice of this major issue? If it's correct what someone here suggested that it's only available in enterprise licences, can they at least make a formal statement announcing that so we at least know? This is f-ing ridiculous.