I believe I did OP register. I clicked that button and in the frames display it logged the frame as it would for any other bone and the animation works just fine when I play it. The only issue is it doesn't when I save/reload. In fact the weirdest thing is when I load the save, the OP is registered on the frames display... just there isn't any information there, looks just like it does when you click OP for the first time.
I'm entirely self taught (which I think we all are) so I'm wondering if its a simple setting I didn't select or a button I didn't click. For saving it you just set up the OP and click OP Register, then when saving you just include that in with the select all bone, facial, display/IK/OP and save and you're good right? Anything I'm missing or anyone have a simple motion I can DL which has an OP in it that I can check?