when you open your folder with tracks, select them all, choose "export" at bottom menu and then GPX and "Share exported data", then final zip files does not contains all tracks? In title of export screen is number of tracks that should be in zip. Is this number same as real selected number of tracks and final number in zip file? I tried now this on two folders and in both cases I get correct result ..
@Žajdlík Josef : very interesting, thanks! You have discovered some new issue in latest Android library! Seems that it takes 10 seconds till existing screen is completely closed. So when you close and open track detail screen too quickly, there will remain more versions at once. I have made a small hack, but it's still not perfect, but definitely better.