When uploading images (a range of PNG and JPEG files) they appear to upload fine apart from that all the previews of the images are simply a blue question mark in a box. This is also the case when viewed on the website.
If I go to edit the image in the Wordpress media tab however the image displays correctly. The thumbnail settings on the same page however do not display it.
Since the image is recognised and displayed correctly in the Wordpress editor I do not think it is a problem with the file itself. I have previously uploaded many files like it and even a couple of the same files from memory and never had an issue.
Any advice appreciated. You can see an example on my site http://www.lukeaylenphotography.co.uk where the logo does not display.