"Also, to be clear, it causes to extent of the KML to be invalid, not necessarily the KML itself. If you zoom into the extent of the flight path, it should be there."
"The change of note from GE changelog:
To conform more closely with the OGC KML 2.2 standard, we've made the parsing of the <coordinates> tag more strict in version 6.1. Spaces must only be used to separate the (longitude,latitude,altitude) triplets…"