SQL Server DB Property Issue
This is a shot in the dark, but since I've seen a number of scenarios where this has fixed odd errors in SSMS 2016, close SSMS, clear out all temporary files using the Disk Cleanup utility (cleanmgr.exe), start up SSMS, and then try this operation again.

Worst case you're no better off than you are now, but you've got a little more free disk space.