I had a similar thing going on, my arms just weren't doing the same motion.
To fix it, I really focused hard on my set up.
Step one was to get my shoulders back. I really tried, but it just didn't happen. I worked on rear delts all the time, but my rear delts sucked so bad,other muscles took over. So I did some shrugs, face down on a bench. Like "Chinese Rows" only shrugs. After awhile, I could actually feel my rear delts, and they grew a little bit.
Now, during moves like face pulls, I can actually feel my rear delts working, and my set up is better. The move that worked for me, may not work for you, but I would try to find a way to get in touch with those upper back/rear delt/lower trap muscles.
I work in "paired sets" for upper body, so I do some kind of row or pulldown between sets of presses or bench presses. At first, I tried to recreate my "press grip" with the rows pulldowns. This was pretty whack. Now,I try to use as many grips as possible for the row/chins/pulldowns. Neutral grip, under hand, overhand, really wide, really narrow, in the middle, whatever. Each different hand position puts the forearms/hands/wrist/elbows at different angles to eachother. This means your shoulders and upper back have to "get tight" at different angles or in unfamiliar positions.
As you go through these "new" ranges of motion, you'll really feel if your arms moves the same or not. Doing really wide underhand pulldowns, or really narrow neutral grip shrugs laying face down I could feel that my right wrist was at a funky angle, or my right shoulder wasn't where is was supposed to be. Using 6 different grips during my B.S. pulldowns was a ton of practice, so my body "knew" how to set up for the presses.