Thumbnails not appearing for all videos in bridge

I've posted this before but got no answers. I'm trying again. In bridge some of my video thumbnails show some don't, I don't understand why this is happening.

Below is an image of what should be the thumbnails but there is only one showing. I can see on that file name that there is an .LS. between the filename and the mp4.

I make a lot of videos with my camera and I use them a lot in my work. So I would really like to understand what it is that is causing this issue.

I've done the following, cleared the thumbnail cache

cleared the thumnail cache and reset

Changed the default video programme from VLC to windows media.

uninstalled and reinstalled bridge

I can see thumbnails in explorer so they can be generated, i just can't see them in bridge. This is so infuriating.

Thanks

I'm at a loss to understand what is going on, this is really important for me to get this fixed.