Hi, I appreciate this is a pretty old thread but did you ever get to the bottom of this? I'm experiencing the same issue - a user is a member of the db_datareader role and is able to run select queries against the tables in the database with no issue. However, they are unable to view the list of tables in Object Explorer. They can however see the table list in Object Explorer Details.

The instance is still on SQL 2008R2 RTM so I'm hoping getting the Service Packs applied will fix this but any information you found would be appreciated.