We're a little out of sync. Objects in my world are PIXI sprites and nothing is CSS, only Javascript.
I'll get it figured out, just wanted to know if there was some caveat. In case it might be a factor, here's how I registered 'spin':
gsap.registerEffect({
name: "spin",
effect: (targets, config) => {return gsap.to(targets, {duration: config.duration, repeat: config.repeat, yoyo: config.yoyo, ease: config.ease, pixi:{rotation: config.rotation}});},
defaults: {duration: 2, repeat: -1, yoyo: false, ease: "none", rotation: 360}});