When uploading images via the Gallery interface, the image order is completely scrambled after upload.
Arc Support Centre have said this isn't a bug, and that the order the images load in is the based on the time it finishes uploading, rather than the order the images are selected in or the image file names.
This idea is to add order tracking for image upload to galleries.
Images are named with a specific naming convention, ending in a number (i.e. FW_1). Images are selected in that order when being picked from the device image finder for the Gallery upload. After the images are uploaded, the order has been scrambled, which requires painstaking re-ordering of the images to the correct order.
This is a huge pain point for the editorial team and causes the simple task of uploading & reordering images in a gallery to often take an hour per gallery.