Key input problem

Hi,

I am trying to leave some key input options in settings as inactive as they only get in my way, for example I cannot use petal mechanics as F keys dont work for me for some reason but the game will not allow me to leave an input blank. I will allow me to assign any key into as many inputs as I want for example I can have every setting signed into E key but I cannot have any input blank. Why is that?

And also When I try to assign any F keys - for example I want to have petal mechanic as F2 key, when pressing F2 duing assignent the game will either quit settings or it will asing it to Enter instead.

Please help. Thanks