What is not visible in the comp view? The entire layer or only the tracker? Trackers are always only visualized in layer view.
Just to ensure the most basic things: The eyeball of your layer is enabled? And opacity not at 0%?
Did the layer disappear after adding the tracker or has in been invisible already before?
Maybe you can provide a screenshot of your UI?
As a side note:
For most tracking tasks, the version of mocha bundled with AE is much better than the old point tracker. This webinar is a good start:
The entire layer is not visible. The eyeball is enabled, and opacity is at 100%. I believe the layer disappeared after I added my tracker. I also noticed I am missing the colored bar within the timeline where the layer in/out should be. Is there any way for me to add this back or do I have to start from scratch?
Um, you're zoomed in real tight on a VERY small portion of the timeline. See that little gizmo at the bottom of the timeline between the two mountain-looking icons? Mess with that slider in-between and see what happens......
I zoomed in but still nothing. Even when I play the entire composition
I would recommend to enter the U key quickly two times reveal all properties you changed in the composition. This allows you to check whether you accidentally changed any properties.
Maybe the position is changed to move the layer out of frame, or the scale is at 0% or you applied some effect or mask that makes it invisible.
It looks to me like the shot has been slid along the timeline until it is out of range. Try pressing the I or O key to move the CTI to the in or out point of the layer to the start or end of the clip. You could try selecting the clip in the timeline and then pressing Alt/Option + Home to move the in point to the first frame of the composition. You could also press the third icon from the right at the bottom of the Timeline to reveal the in and out point columns and check to see where they are set.
I am having the same problem with ae 2015, using graphics created with after effects. Its pretty sporadic, and seems to be temporarily fixed through a restart of ae. Nightmare of a bug.
I'm on a mac platform btw.