1) Choose a MySQL connection and open the Query Builder for the first database in the database dropdown list and this database should not be the default database for the MySQL server.  For example, "ac10" is the first database in the database dropdown list and "mysql" is the default database.  I open the Query Builder for the "ac10" database.

2) Build any query and execute it -- it runs fine.

3) Save the query.

4) Re-open the query.  Note that "ac10" is specified in the database box.  However, when you execute the query, it complains that mysql.table doesn't exist.  The database context for "ac10" is not being set.