How can a put only the X tracking data on my null/etc.?

[Darby Edelen]

I would apply this expression to the tracked Null’s position:

[value[0], thisComp.height/2]

Which will limit the tracked Null to moving only on the x-axis and centered vertically in the composition.

Then you can parent another Null to the tracked Null to control y-axis motion. If you’d like to make sure you don’t accidentally move this one on the x-axis you could apply this expression to its position:

[0, value[1]]

Darby Edelen