It looks like 5.1.6 doesn't render DISQUS. Everything was fine in 5.1.5 and now it's just gone. I've verified the settings and nothing appears to have changed on my side. Cache is cleared and tried with Chrome and Firefox. Something to look into.
Disregard. You have a new setting in 'View' > 'Entry' > 'Comments' > "Show Comment Form". A little misleading, as most of the comments functionality pertains to your built in comments. Nevertheless, there's the solution.
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