What does your teacher have to say about this problem?Overall, I'm guessing you've jumped into playing this too fast, without having done the preliminary slow and careful pre-work.I see you've worked on no 41 which is also for the LH - - did you have tension problems with that one? I'm curious, is it a LH only issue? How about op 740 no 50 - that's quite a demanding piece for RH - did you have a tension problem? If not, study what the RH is doing right, and the LH is doing wrong.
She told me to just "wiggle" the forearm
I usually have tension with everything, I had tension with the left hand on number 41 and on the right hand on the 50, but not as much as in this one.