Why have my document previews suddenly disappeared?

I don't know why but a couple of days ago all my file previews disappeared. I'm a photographer and need to see the image previews so this is obviously quite a big issue.

I'm using Windows 10 pro.

I have checked the settings in 'folder options' and unchecked and rechecked the 'show thumbnails instead of icons'.

I've also checked in performance options that this is setup and again unchecked and rechecked but this didn't fix it.