Google Maps in Safari suddenly stopped paying attention to mouse wheels

Like, really suddenly: I was on a Google Maps view in Safari, in the process of zooming the view in, and it stopped. I'm not zoomed in too far or anything, and I can still double-click to zoom in (I don't know how to zoom out), and dragging the mouse drags the map. Basically everything works like it was working 10 minutes ago, except mouse wheel scrolling. I have two mice hooked up because of a weird monitor arrangement. Both still work (I mean the wheels still work) on other Safari windows and other sites, and terminal windows etc. Shortly before this broke (I can't remember exactly how long, but not more than a minute), I experienced one of those things where Maps just fails, probably because a JavaScript update was needed. Thus I suspect this is probably a bug Google introduced, but I'm still curious. I have restarted my machine shortly before posting this (and after it got weird), so it's a new instance of the Maps window. (I don't know how to do a "force reload" with Safari, as a fairly new Mac user.) Also I tried it on a Linux machine with Firefox in a freshly loaded window, and it's fine. I don't think I accidentally changed anything, because literally all I was doing was rolling the mouse wheel. It's weird.