Tried uploading images today, and it's not working. First, I assumed maybe that Steam (image source) had done something suddenly to disallow the import of images, as some sites have done in the past. So, I saved the image to my hard drive. But, then it's not allowing the image from there. So I looked for an image on a completely different website, and it's still not working. Considering that I've seen a few new games added today without images at all, I'm assuming I'm not alone.
All of the images were coming up as broken in my previous images section, but when I went back to it after navigating away, all of the broken images were completely gone. Using Windows 10, tried on FireFox + Chrome.