Missing gallery thumbnails…..

So all of a sudden images in my tiled galleries are vanishing at random from the thumbnail mosaic on every page on my website. Despite a broken image placeholder being seen you can click on the image and it will load as it is coming from i0.wp.com or i1.wp.com etc…. not very useful when the thumbnails are missing….

Have tried deactivating every other plugin – same result
Have changed to a default theme – same result
Have rolled back Jetpack to over 6 different previous versions – same result.
Have flushed every cache in sight – same result
Have deleted and reuploaded images – same result

I cannot remove and reupload every image as the vanishing ones are random and I have over 5000 images on the site….

Any suggestions from the developers per chance? This is clearly relating to Site Accelerator – tried that on and off – same result…..

ANy suggestions from anyone? I cant even remove the i0.wp.com references as if I disable jetpack then all the tiled mosaic galleries just revert to the very basic WordPress chunky gallery view which looks as good as a melted boot….

The page I need help with: [log in to see the link]