Ingame Chat-Line Command Parser deleting Arguments

When i write a command in the Chat-Line,

the Command Parser is deleting hole Arguments when i give the input "keyboard_arrow_left"

and i must rewriting the hole command or argument.

I think this Bug comes often when i change an already in past executed command.

I hade it.

It comes not every time but in some cases, i dont understand why and when, this bad command parser behavior comes.