HLS: skipping forward plays audio but not video
I've just implemented JWPlayer with my server, which uses libav to autogenerate different video formats. I'm primarily interested in using JWPlayer so i can use HLS.
I'm testing with the Big Buck Bunny video in Firefox
When playing a generated HLS video the audio and video plays fine, but if I skip forward I only get audio, the video shows the last frame prior to skipping forward.
I'm guessing this is something I need to tweak in how i'm generating the video or m3u8 files, but without any diagnostics from jwplayer I'm at a loss as to where to start.
So, firstly, is there any obvious erros of mine which would cause this to happen?
If not, is there a debug log or something from jwplayer that would tell me what its not happy about?