I have a pdf file displayed via gview in a page. In this pdf file are links to jpeg files, to which I've recently added a few more. The old ones display correctly when clicked but the new ones don't. The pdf and the jpeg files are all stored on the host server filestore - not media library - because I prefer to use a folder system that I can understand and that mirrors what have in my local dev filestore.
After several days of trying various solutions from .htaccess changes, permalink updates and the like, I studied the server filestore and discovered that the older jpegs were marked as filetype 'Other file', whereas all the new ones were marked 'JPEG'. The Jpegs old and new are all 800 x 600 pixels. Moving an old jpeg file to the new folder on the server filestore kept the marking 'Other file', but moving a new jpeg to the old jpeg folders did not apply 'Other file' to it and would not display.
Any ideas how I can fix this so that they display? I'm quite happy to find a way to mark all new jpegs as file type 'Other file' if that would solve the problem. Incidentally, tif files work but not very well and, as I have about a thousand new jpeg files to upload over the coming months, would prefer not to have to do a grand conversion.
It may be relevant that the old jpegs were copied to the server file store by ftp - which hasn't been upgraded since - a year ago, but the WordPress version has been upgraded in that time.
Any help will be very gratefully received.