Hope this isn't too trivial.
Right clicking 'data connections' in server explorer of VS2019 - to 'Add Connection' , results in a 'the file is in use', 'enter a new name or close the file that's open in another program message.
The database I'm trying to connect to was originally downloaded from Azure Sql server, and it is not 'in use'.
The puzzle is that I can connect to the same db with SSMS 18.8. I thought I could maybe try exporting it from SSMS - but given all the export options in SSMS couldn't manage that either.