Bugs dont touch the ground

[D88M]

Hello, i recently started the game again and while playing as the chestbuster i saw that when bugs land they dont touch the ground but land on a empty space above the ground, how can i fix this?

[x-M-x]

Hello, i recently started the game again and while playing as the chestbuster i saw that when bugs land they dont touch the ground but land on a empty space above the ground, how can i fix this?

Is it always happening and on every level?