Bobbles Thank you very much for sharing files.
I have checked and I can see the same issue on my PC in Tonfotos. However, I also checked opening this file in few other applications, and I got mixed results. Some opened it fine, some had same issues. This is Snip & Scetch (built-in Windows app):
This is another built-in Windows app Photo:
Same thing with Mac OS built-in app Preview. However, at the same time several applications showed file without issues.
My guess is, files are broken, but not entirely. Typically, RAW files contain both original image and smaller JPEG version as preview. The apps that will not bother decoding full image and just show JPEG preview - they will show your files just fine. But image editors and other applciations like Tonfotos will try to decode original image, and this is when it shows corruption.
Hope that makes sense to you.