For some reason thumbnails of attached JPGs are no longer showing up on my Trello cards, and the option to choose one of the images to 'make cover' is gone. Can anyone help? I've got cover images enabled in settings and all my old Trello cards are fine, it's just newly created ones. It's not just happening on my PC either so it's not a storage issue - it's happening on my client's PC as well, when she views the same Trello cards.