You will only see tables for which you have privileges. If you have the DBA role, you may need to check the "Use DBA views if available" preference (Tools > Preferences > Options tab page).
I checked and the use dba view option is checked.
looking at what is displayed in the drop down list. It seems to only be the tables under my oracle user, even though I have the dba role as my default role.
is there something else I should check?
I checked this, and it seems that it indeed true that only tables owned by you are listed. Other tables need to be typed in manually and can not be selected from the list.