Hi,
there is a problem with playlists on Android. I don't think it's a bug, but a usability problem.
When you go to the settings and change the media directories, playlist contents are deleted. In my case, I first removed the SD card directory and then selected two of its sub directories, because I don't want VLC indexing everything on the card. The items in my playlist were located in one of those sub directories. When I returned to the playlists, they were empty.
I get why this happens, but it shouldn't happen. First of all, the files are still available, so there's no reason to remove them, even if the directory they are in is not a VLC media directory. And then, even if the files were deleted, it would be better to keep them in them in the playlist so you can at least re-create the playlist. Users spend hours creating their playlists and they shouldn't just be emptied like that.