Do note that you can't currently message users on other instances from kbin. The button will still be there, but it will bring you back to the homepage. I believe Ernest said something about it being "unimplemented," so I'm assuming cross-instance messaging will happen someday, but is probably not a high priority at the moment.
Successfully blocked the second two magazines about two minutes after this post but @news_us_politics is still giving me errors. It doesn't seem to be particularly consistent.
@uspolitics. I'm half suspecting the error might be related to how many requests I've already made to block things recently, since I was having no issues going through the first couple of pages and blocking about half the magazines on them and now suddenly am encountering a bunch of errors? But I have no actual evidence for that.