David Alcock unravels a mystery:
I was browsing the SQL Server subreddit earlier where someone had posted a problem where they’d been able to take a database offline but couldn’t bring the database back online via a script or the UI in SSMS (full thread here).
There’s a bit of a back story; all the DBA’s have left the business (facepalm) so a non-DBA has been left with the admin type tasks. Secondly the reason the database was being taken offline was to take physical backups of the databases mdf and ldf files (double facepalm).
That is its own issue but read on for the problem at hand.