I noticed something today. If I update the mp4 chapters with over 100 chapters with foobar 2000 1.5 beta 20 everything seems to work right. But when I open the file in foobar 2000 1.4.8 or foobar 2000 1.4.4 it only shows 1 track with ? in length. When I try to play it I get.
"Unable to open item for playback (Unsupported format or corrupted file (invalid index map)):"
foobar 2000 1.5 beta 20 seems to play it just fine with all chapters correct.
When I updated chapters with less than 100 chapters it played all right in all versions.
I can add over 100 chapters with ffmpeg or mp4box and it plays ok in all the versions.
ffprobe & mp3tag does see all the chapters correctly.