Hello Vid.
Thanks for your suggestion, it actually did the trick and now it works.
So I add this part of information that was missing from my original post;
I generated the KMLs in QGIS and I tried to upload them to the 3DSurvey Pilot app. This probably made the app crash (?). I did as you mentioned, opened the KMLs in GEarth and exported them again as KML and imported them to the APP and worked with no issues at all.
Thanks for your suggestion!!