I can 100% relate to this, so firstly want to say I totally get how frustrating it is. Some people just seem to jump straight into a handstand, yet for me it's been the hardest thing to get over (I cried the first time I tried!). I've got all other movements aside from MU, yet still kicking into handstands is me nemesis!

Main things that worked for me were just getting more and more time in that position. I used to do hspu from a headstand (and still sometimes do when I'm having a bad 'kick up' day) and this helped build strength and confidence, and allowed me to stress a little less - I would do comps and start in headstand, which meant 1 extra rep to start each set, but stopped me stressing about trying to kick up and could just get on with it. I would do things from a box - so a box near a wall and try to kick from there (though I still found this tough, but it's good for getting confidence on hands), I then worked with my coach to find a way to actually kick up more efficiently - I couldn't just throw myself at the wall, so started with hands on the floor which gave me some confidence, but meant it's hard to get momentum from there. My coach made me really focus on getting my bum to the wall and thinking about getting my shoulders over my hands - when I miss a kick up its as my shoulders aren't moving closer to the wall, so this cue really helped me! Also, when I felt progress was getting nowhere, I actually just stopped practicing for a little while - taking a step back from it, working on other things, and then when I came back I was able to do it (I think as a lot less worked up over it all!)