position bar problem with x264 files

Hello anyone,
I haven't seen this problem reported before (possibly I didn't look hard enough) but it is present on three different installations of Kdenlive 0.8.
I cannot skip through a clip using the position bar, moving the the bar in any way results in the video simply fast forwarding. That is moving the bar along a 25 second section or clicking the bar 25 minutes into the clip, the monitor simply advances as though playing at double speed. This problem only occurs with x264 files, I know I should transcode but currently I am just taking screenshots of a large collection of Videos for a book, transcoding should not be necessary for such a simple process.
Has anyone else come across this issue? or better yet can anyone help me resolve it.

Many thanks

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