Will he run ahead to a toy laying on the ground? So you stand still in front of the jump with him at your side, holding his collar. Throw the toy (or bait bag, or whatever he likes) over the jump, wait for it to land, and, while he's focused on the toy, let go and give him your jump cue while you stay still. Once he's over the jump and at the toy, you run up and play with him (or open the bait bag for his treat, whichever you use).
I'd also do the opposite if you have a stay on him (or if you have someone who can hold him if needed). Set him up in front of the jump, tell him to stay, lead out to a few feet past the jump, drop the toy right next to you, then release him to it. Stay still until he gets the toy, then play/open to treat/whatever.
Basically, I'd find a way to take your movement completely out of the equation at this point, and just work on "focus forward, take the jump".