GPX editors see empty folder

I have some gpx tracks recorded using OsmAnd. I can see the files using my browser and also the app "GPX Viewer" can load the files and display the tracks on a map. They are located on my external sd card at (...) /Android/data/net.osmand/files/tracks/rec However when I want to open the tracks in an editor, to change them, the "tracks" folder shows empty. This happens with all three apps I've tried: "GPX Track Editor", "Rambler GPX Editor" and "Simple Track Editor." Any suggestions?