Performed a thousand times and suddenly no longer possible. If I want to assign an action to a joystick button (e.g. camera view), I have to click with the left mouse button in the field “Start review” to activate the field for an input. Then the left mouse button is immediately entered in this fi…

I do not think that is your mouse, most likely that is a small signal from the controller axis that is being transmitted constantly, so the second you click the spot, the signal displays. You could try adding a dead zone for that axis, that may stop it (as mentioned above by NIKoTin34230)