Thanks @Nostrildumbass , this is a great explanation to an issue that I’ve struggled to figure out for a LONG time. It’s insane the official documentation doesn’t explain this so simply, but I’m happy to say IK is finally working perfectly for me, now.
I’m reviving this thread to add one piece of info that tripped me up… the “Transform to Bone Space” node will only work with bones, not sockets. Maybe that’s obvious to some, but I assume they were interchangeable and they are not. Cheers!