Permissions issue in SSMS: "The SELECT permission was denied on the object 'extended_properties', database 'mssqlsystem_resource', ... Error 229)"

Please check that you didn't check db_denydatareader DB role. By removing that check it worked for me.

I had similar problem and resolved that by removing two roles db_denydatareader and db_denydatawriter for that user and add other roles. I used sql management studio.

SSMS tries to get the extended properties of the table using fn_listextendedproperty. According to MSDN the required permisions to view a table's extended properties is

ALTER on table OBJECT

Your login test should have this permsision as owner of the test table (it is the owner, right?). But even if you don't have permissions on the table, the query for extended properties should return emtpy result set, not access denied. The fact that you get an access denied error on a sys object in the resource database indicates that the code signing of the system resource database (mssqlsystemresource) is broken. Did you drop any of the '##' certificates from master? did you manually altered any object in the resource database?

Anyway, you have a what looks like a corrupted instance at this moment and I'd recommend you contact product support on how to get it back into a coherent state.