The 16.5.2 release of SQL Server Management Studio (which reports as 13.0.16105.4 in the About screen) has a bug where you cannot display a list of tables in databases that contain sparse columns. You get a “Subquery returned more than 1 value.” error as shown below when you try to expand the Tables node.

This has been reported here and here.

Upvote the Microsoft Connect Item here.

The fix is to roll back to a previous version.