Specifically, sometimes it works with my Safari windows ans sometimes it doesn't.
And sometimes when it doesn't work, Option+< will work for some reason.
But sometimes that doesn't work either and then I just have to swipe and slide or use alt-tab (yes, you can now install a program that gives you proper alt-tab, so I do not have to deal with this IMO nonsense, it just feels like the right thing to do when I know I'm just looking for the other Safari window.)
I'm not complaining, I knew what I went to when I asked $WORK for a Mac, I have had one before and for me the tradeoff of having a laptop supported by IT and with good battery time is worth it even if the UX is (again IMO) somewhat crazy for a guy who comes from a C64->Win 3.1->Windows 95/98->Linux (all of them and a number of weird desktops) background.