The FPL file is an XML using a specific format indicated in the header.
It seems the address has changed from what the GNS is writing or reading. A quick google search gives:
<?xml version="1.0" encoding="utf-8" standalone="yes"?>
<xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns="http://www8.garmin.com/xmlschemas/FlightPlan/v1" xmlns:fp="http://www8.garmin.com/xmlschemas/FlightPlan/v1" targetNamespa
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