Probably a few things..... small things though.....
PoB is right - jumps that small that close to a top end will suck it out of you. That, and needing some talc on your legs ( or just leaving your shorts down) could have been the difference between getting and missing this.
But, I'm happy to see a miss because that helps me see weaknesses which will help me help you....... damn, that's a lot of helping.... LOL
1st off - you wasted 12 seconds of your life talking yourself in to how heavy it was going to feel. From the point you got the the bar to when you bent down to grab the bar. That's a clear sign that you were either 1-tired, or 2- unsure about the weight.
2nd, you dropped straight down to start your pull instead of sitting back in to the hamstrings and loading the bar. Part of that is technique, part is weak hamstrings. You can fix both with chair deadlifts ( look them up on Laura Phelps' youtube) .... and some box squats..... to put it in perspective, I pull mid-700s and when I pull the slack out of the bar and sit back, before I even drive my legs anything under 600 or so will come off the ground.
Speed deadlifts can help a LOT too. Practice getting yourself tight and pulling the slack out of the bar, then exploding off of the floor to start the pull.
3rd, work some rack lock outs against bands ( hold for 3 sec at the top), and belt squats if you can. Those will build the hamstrings and glutes. Right where you missed your hips came forward, butt tucked under. My wife has the same miss and it's all from weak glutes. Part of that lock out could also be technique. Once you're above your knees all you need to do is keep your head up, squeeze your glutes, and try to push your belly out. Or, it could just be that you were tired and got impatient and tried to jerk it to lock out ( and couldn't) instead of just squeezing your hips through and grinding it up.
The strength is definitely there though.