I found a troubleshooting option that appears to have worked! I used a colleague’s account on a different Macbook which I connected to iPhone hotspot first to access the file and all of the images reappeared! From there I saved a local copy of the file (File>Save Local Copy) which I then moved to my laptop and imported back into figma.

Interestingly after I had finished this & went to check the original file with the missing images on my laptop and normal internet, all of my images had reappeared there as well.

This problem needs to be fixed, I now know I can’t trust Figma’s image servers at all.