I have now got this working using the ODBC Driver 17 for SQL Server. I think there should be some updated guidance on how to set this up, from start to finish, as the current manual is a bit vague.
I would like to know what BackgroundHALShouldPause does, and how to use it. While it's listed in the HAL Primitives report, it is not used in source code and it doesn't appear in the LMS HAL...