I am a C+ plus player at best and probably not one who should be giving advice but I have been having issues with the same shot.
Just this weekend I had a break through, it may or may not help. I realized that my mechanics were at issue, I thought it was an aiming issue but it turned out that I was chicken winging! It is subtle but all my shots, I was slightly coming across the CB and and applying unwanted english. I started working on really focusing on getting my arm and elbow tucked in and inline with the aiming point and low and behold success. I had never been able to get the ball to draw doing the mighty x and now as if like magic, it draws almost all the way back. I have a lot to work on, but realizing this mechanical error just fueled the fire
Goodluck!