So, I want to do this: https://www.youtube.com/watch?v=C-ThAVlaMZY - but I can't do the long/high jump to the left direction - as in, the character doesn't perform it, even though I press the right buttons (Up. Left and Space*) - the jump to the right direction works just fine, but to the left, it just doesn't happen at all. What gives, and how to fix/handle it?

*I tried so many times it's not even funny, so I'm sure that's exactly what happens, or rather not happens.

Edit: it worked when I used WASD keys instead of arrow ones, but it's still bloody weird and annoying (I don't want to play using WASD, and want the controls to work the way they are supposed to). Any ideas why that happens and how to fix it?