Taking a stride out when jumping?

[Thefatcob]

After spending years (Literally) building my cob's confidence over jumps, we've now hit a new issue. He won't add that extra stride before the jump, he takes an entire stride - sometime he'll even attempt to take 2 out - and I'm not going to lie, it's a tad scary. I've tried holding him back, i've added poles before and after the jumps to sorta 'mark' where his strides should be but he will just take off at the pole. My RI suggested I don't canter till two strides out but then he just pings over and he doesn't seem to use his back end. RI also had us do it on a circle, cob still took me for a flying lesson. I tired not holding him back and letting him figure the striding out but again, he picked the flyer.
He does this on the lunge too. Any tips, or exercising we could to help him learn that he needs that extra stride?

If I hold him back too much, we lose the momentom in the canter and he slams the break on, so it's a fine line with him.
He does this with everything as well, Even my RI said it's an odd thing and that just maybe how he likes to jump.

 

[Jessey]

I’d work from the trot for a while, you say he doesn’t use his back end so well but breaking the habit of long jumps first then reintroducing the canter should hopefully sort that.
One other thing I’d watch carefully for any discomfort behind, the fact that he struggles without momentum and isn’t using his back end on a normal stride at a slower pace could be indicators that something is going on. I wouldn’t panic, but I’d consider it.