Constant Animation Enum doesn't work?

I’m currently making some animations for a project.

Long story short, I’ve been trying to animate using constant as its much better for the type of game I’m making, which requires a quick response, so I’ve put constant for the animations, yet after the first keyframe the animations starts running at a linear tween, rather than constant.

Has anyone else had this issue and if so how did you fix it?

Thanks in advance.