Converting Lines or Polygons to GPX in QGIS for Avare

[Batu]

Hi, 

I am a scientist designing flight lines for our campaigns. I am looking into Avare as a possible solution to provide our pilots, so that when we provide them the flight lines, they don't have to type it in their own systems, but can follow the flight plans in Avare. 

Our flight plans are a little different than flying to a destination, we usually only plan the science observation lines that we are interested in collecting. So they tend to have a racetrack or figure-8 like setups over a certain area. 

Attached I have two GPX files. The first one (MESA...), I was able to read with Avare, but only the first flight line is shown. The second one (GJT...) is a racetrack and I couldn't make it work with Avare at all. It does not show up in the list when I place the file in the user plans folder. 

I prepare these lines in QGIS (in shapefile or gpkg formats) which then I export to GPX. Any ideas what I am doing wrong?

All the best, 

batu.