Hello! I am a Student. The pdf previews aren't working for Canvas on PC. I am using Chrome (and even updated it). 
I also tested it out on Firefox and Microsoft Edge and doesn't work. Every time I press "preview", the blue circle is just infinitely there. I uninstalled my Honey, any Adblocks, and more as I thought that was my problem. I also cleared my cache and cookies to no avail. I would appreciate it if someone were to be of help! It use to work before but suddenly it doesn't, the previews work on Mobile. I haven't downloaded anything new to my Chrome on PC.