Upfront Child Themes are downloading with pixelated images

I'm trying to download Upfront and it's child themes, however when I do, the resultant child themes images are all distorted. I'm running into an issue on my site where even the Upfront editing feature isn't loading, so I think that the issue is related.

How can I get these 5 themes installed on my site without any download corruption? Is there a way I can uninstall them through the dashboard?

Attached is the header image from Spirit as to show what's going on.