I have finished making a realistic dragon in Zbrush and I am done rigging it in Maya with joints and IK handles, but because the IK handle moved outside the joint in the left hindleg and I could not not make it look exactly like the other hindleg from the side, I deleted the left rig for the left hindleg and decided to go to Mirror joints.

I had marked the entire rig in the right hindleg.
Wrote in these settings; Mirror across: YZ, Search for; R, Replace with; L. I have also tried switching the R and L. And clicked Apply. Nothing happened.

I am sorry if it is obvious - I am new and confused as to why it does not work.

I also can't select joins anymore by clicking on them.