As far as I see, there are the same tables on my Oracle Databases for boths ways. I did not experience so far.
But if you know the correct scheme and table name, you could do the following:
You can put the table name and scheme name in a script like below, then you should find your table in the visual mode of Query Builder.
This script you can save from query builder via red triangle button ("Save Modify Query Script"). Maybe you need to open just another table, to get that script, and than put in the right table name into the script to get your table into the visual Query Builder.
New SQL Query(
Connection(
"MY_DSN"
),
QueryName( "QUERY_NAME" ),
Select,
From( Table( "DATABASE_TABLE_NAME", Schema( "SCHEMA" ), Alias( "t1" ) ) )
) << Modify;
Georg