Maybe something is happening in your other session that is NOT happening in your SQL Developer session - this may trigger a security feature in the database.
Are there any scripts you run in your other tool when you connect (login.sql), or perhaps there is a logon trigger in play?
Not really Jeff.
The only difference is Windows OS vs Mac OS. I see issue in Mac OS version only.
there must be something else - the db could care less what OS the client session is originating from