How can I keep Control Rotation from freaking out past 90 degrees?

I’ve looked all over for a solution to this and I’m coming up short. I’m not even sure what is going on. If I’m telling Pitch and Roll to be something specific every tick then why do they get influenced at all outside of that? You would think they would always be the result of the BP above. Additionally why does Yaw start to lose it’s orientation as I walk up the slope. Isn’t Yaw always the swiveling down the UpVector? Instead it starts to act like it’s only yawing along the world UpVector and as I get near or cross the 90 degree mark it’s rolling the character onto it’s side.