Parent constrain breaks twist

[Stephrobert18]

Following along with part 22 of the Maya Learning Channel's advanced rigging YouTube series, I am implementing the twist onto the right arm of my character. I mirrored across the joints and geometry and created the IK, FK and twist once again through the videos. However, towards the end of the video the bind joints need to be parent constrained to the result joints, however whenever I seem to do this the twist stops working. The joints do not move at all as if they're locked. I'm not sure whether it's do with the joints orientations or they've been mirrored over. I have attached the scene file if anyone is able to help me at all! Thank you!

[hamsterHamster]

Hard to sort through the unfamiliar, partially locked rig, however it seemed that the cause of the trouble could be somewhere in the rightArm_IK .. the control doesn't seem to bend the elbow correctly. In any case, the leftArm seemed to work fine, therefore you already have the working example.

[Stephrobert18]

Yeah I had seemed to figure this too, and wonder is there a way to go back and redo the IK without breaking the twist etc? The geometry also doesn't move with the IK/FK controls so I don't know what's gone wrong there either

[hamsterHamster]

I wasn't sure which thing is doing what. You can locate the IK handle, delete existing and create new one, make sure the IK arm actually works, save this as a milestone backup before you connect it to the switch, so you can step back if something goes awry.