I've tried deleting these files and reuploading them, but to no avail. The only thing that works is if I upload them under a different file name, so I suspect this might be a caching issue. I know for sure it's not browser caching because I've cleared and done Ctrl + F5 multiple times.
One thing I've noticed is that it doesn't happen with HTML and .txt files. Those file formats seem to update as per normal.
Does anyone have any insight on the matter?