Whew! What a chore that was, tracking this little thing down. It's a browser add-on called Privacy Badger. It's a "browser add-on that stops advertisers and other third-party trackers from secretly tracking where you go and what pages you look at on the web. If an advertiser seems to be tracking you across multiple websites without your permission, Privacy Badger automatically blocks that advertiser from loading any more content in your browser. To the advertiser, it's like you suddenly disappeared." - quote from the Electronic Frontier Foundation (EFF) description of Privacy Badger.
Unfortunately, it made me disappear as well, as far as commenting or replying to comments on this blog. Fixing it was easy. It just took moving a slider bar over to "accept a domain." Now, I can comment just like I used to.
I've had Privacy Badger installed for a couple of months, so I'm not sure what caused this SNAFU to occur, but, in any case, it's now fixed... I think.
Other than this problem (turns out it was a minor problem), Privacy Badger does to a great job of what it was designed for. You just have to remember to check the settings once in a while. You can download Privacy Badger, free of charge from (https://www.eff.org/privacybadger).