SRs, too.
I got a SR drop from one of my Rags about 3-4 raid events ago, then another SR a few raids prior to that.
and I don't use BP on raid events, only h/e + soloing expert/rags... and getting way over 10M PP each time that's a goodish representation on how low the drop rates are, I guess... but I still think I got lucky lol

and to be noted, you can ONLY get drops from your own Ragnarok battles, not others. (and I doubt expert?)