Problem with my model's hitbox

Hello,
I created a model with Blockbench which is not an entire block. So I try to get the hitbox to be in the middle of the block but it doesn't work, one part works and the other part doesn't.

Here are my settings: https://imgur.com/nxjhlyn

And here, the in-game result of the parameter: https://imgur.com/KHuPwOC

The "red" things are the parts that work well but it's still the "blue" part where the hitbox doesn't do what I want. If anyone has the solution where I could have gone wrong. Thank you