Got a new Mathews Vertix and I’m having trouble holding my pin on target. Do you believe it’s just lack of practice or is there something I can do to help resolve this problem?

There could be a few factors at play here.  First, it's important to understand that your pin never "stays" on the target.  No matter how much we practice or how many weights we lift, the pin doesn't freeze on the bullseye when we shoot.  Instead, it "floats" around the bullseye as we aim, pull through the shot, and release.  If you do it right, the arrow finds the middle most of the time.  Now, if you're still struggling with finding the middle of the target, you may be simply pulling and holding too much weight.  Shooting more and working out to build muscle can help this, or you can try backing your poundage down a bit.  You can also look into a longer or heavier stabilizer.  As the name implies, a stabilizer will help stabilize your bow while at full draw to make aiming easier.