So I posted about this awhile ago and I found the culprit, but I’d love it if you guys could fix it. Here’s the original post: PDF won't load in browser unless it's downloaded (i.e., local)
The problem turns out to be an extension I’m using. The extension if pretty awesome, so I want to keep using it. It’s a bit of pain to keep turning it on and off.
The extension is Reverso Context for Chrome and Firefox v2.2.202
If I turn off the extension, I can view PDFs without downloading them no problem. Otherwise, I will get a blank page unless I download and open the local copy.