NetWorx stores all its configuration in this file NETWORX.DB. If the option is not ticked, it means it's not set in the DB file.
You can check this by downloading
SQLiteSpy, loading NETWORX.DB in it and running the following query to check the setting
SELECT VALUE FROM config WHERE PARAM = 'IgnoreLAN'
A zero means it's off and 1 means it's on. It can be set by running the following query:
UPDATE config SET VALUE = 1 WHERE PARAM = 'IgnoreLAN'