Whenever you see default items mixed with the airport, it's always a problem caused by another scenery.
The most common source of conflicts are those AFCAD supplied with AI Traffic products like MyTraffic or Traffic 360, etc. Those files shouldn't be used if you have an add-on airport, they are supposed to used only if you have the default scenery, so you must remove every AFCAD for each airport you have an airport add-on.