Fragmented MP4 takes ages to start playing, or never

Is it trying to accumulate all the indexes of a file before starting? If it was a live stream then VLC would never start.

On both Win10 and OSX Mavericks I have tried

VLC 2.2.2 VLC 3.0.0-git-20160224-0402

Using a fragmented MP4 via http or as a local file.

DASH streaming works in 3.0 though (it's broken in 2.2.2). Doesn't this use fragmented MP4, so why does it work there?

To generate a dash-compatible fragmented MP4 using ffmpeg: ffmpeg -i yourinputfile.mp4 -c:a copy -c:v copy -f mp4 -movflags dash fragmented.mp4