For some reason catalog images are not uploading properly, with no error messages or anything in ./var/log/exception.log or ./var/log/system.log or /var/log/httpd/magento/error.log - simply it just seems to ignore the image file.
Perhaps relatedly, catalog_product_entity_media_gallery doesn't seem to be updating at all when I upload product images, hence uploaded images show in the front end but not in the back end at all. On re-save they are removed.
I'm unsure where to start with debugging, been looking around for a while with no luck!
This just started happening a few days ago after importing a few products. Before then it was working fine.