looks like the orient constraint for the driven joints isnt hooked up properly so its blending half way between the two?
I find the best way to set a simple ik / fk switch is to just use a bend colors node in the hypergraph. IK/ FK switching is essential blending between two vectors. And So if you hook up your FK to color1, IK to color 2, the blend attribute with your switch control and the output to your driven mesh you get a very reliable simple blend.
Its hard to debug a rig with screenshots, if you still cant get this to work post your file.
FX supervisor - double negative