audobooks not playing in order -- please help

I just got a Clip Sport to replace my beloved Clip+ that recently passed away after years without trouble. Since I only use it for audiobooks, this is really a major problem. I’ve tried all the workarounds above: new firmware, renaming ID3-tags to “Chapter xx”, nothing works. The problem for me is that it It doesn’t even recognize m3u playlists, it just states that the file format is not supported.  

Will you guys at Sandisk ever solve this? Otherwise, the player is simply useless.