I have noticed something like this from time to time (I hadn't noticed any consistency to it) where the blue arrow icon did not seem to accomplish anything. On closer observation, when you click the blue icon, although nothing visibly happens in terms of jumping to the right post, I've noticed it /does/ seem to update the intended URL in the browser bar. So, as a workaround at least, if you click into the browser bar and then hit enter, your browser will then load the updated URL as if you were visiting it for real, after which the page will reload, may stall in the wrong place for a few seconds, but eventually it processes the #xxxx anchor and does (finally) jump to the right post.

Not as great as when it "just works", to be sure, but until/unless IB is able to fix it, you can give it a try...