Yeah, so I just whitelisted LFGSS and lo, the following button reappears. Soz for false alarm.
I think I maybe accidentally murdered it in one of my many ongoing attempts to get those wretched "SUBSCRIBE TO THIS WEBSITE" modal popups permanently out of my face.
Edit: turns out that I didn't accidentally murder it at all, and that actually "subscribe-button" is nixed by fanboy's "Annoyances" list. So there we have it.