KDFW taxilines aren't made with the AFCAD. If you edit the AFCAD, you must be sure your editor doesn't change the Exclusions we programmed, otherwise the default scenery might pop up.
If you have a duplicate, because you saved with a new name, chances things will disappear at random.
And, be aware that, if you save the AFCAD with another name (meaning you will have to remove the original one), the original one will be restored automatically when you install the Stand-Alone Addon Manager, for example to do a GSX Major update, so this will create a duplicate.
And, if you save with the same name of the original one, during the update your modifications will be overwritten and your file will be saved with the current time/date with a .BAK extension.