Yeah, I don’t either. Safari 10.1.2 in Yosemite it works on first load, but in Safari 12.x in Mojave it doesn’t. But if inside Inspector I go in the resource ihotspot.min.css and delete the attributes -webkit-animation: Ani 2s infinite + animation: Ani 2s infinite in the class .pins_animation.ihotspot_pulse and subsequently undelete them, then the animation starts.
I’ve confirmed this behavior with several other Safari users, so I know now that it’s not a conflict isolated to my Macs. Does this info trigger any possible solutions in your mind?