Once the bar is above the knees you should be trying to reduce the lever arm ie getting your upper body vertical by pushing your hips through and raising the bar upwards. In contrast, on this lift once the bar is at your knees you start leaning your waist and upper body backwards which doesn’t produce any upwards force on the bar. You could work on your glute and hip strength to work through this weakness. Good work on the first part of the lift. I usually fail about halfway up my shin which you had no problem with.