A 200 should work. Does everything work if you 
DNS for marketplace?
It’s a mystery since so many other files work with no problem. It’s also not consistent for me. I would get a lot of 520 and 521 errors for .js files, but later they would all work. Right now, only styles-m.css and home-eco.jpg aren’t loading. Those are the two that never work for me (in Firefox). In Chrome, only home-eco.jpg isn’t loading.