Time Remapping is deleting parts of my clips?

(new user so pardon my ignorance)

I'm using time remapping to slow down the video at the end of a clip. It worked fine the first time, but when I go to adjust it there seems to be a bug. For example, when I try to decrease the speed at the end of the clip, it actually makes the clip shorter and cuts off the front part. When I increase the speed, it does the opposite and makes the clip longer. Any ideas?