I tracked the footage to a point, applied the tracking data to a null object for other objects to parent to, decided I wanted the object to remain on screen longer and thus had to track further, went back to simply keep tracking from where I had stopped on the timeline so I could reapply the data. Found that I cannot reuse the tracking data once applied, the "Edit Target" and "Apply" buttons are greyed out. So now I must reset and retrack from the beginning.
Not normally a big deal, but my computer chugs away dealing with the 4K footage. Slightly annoying, but hoping I've just got it wrong.
You can apply the same tracking data multiple times. You can add to the duration of your track too. All you have to do is to ensure that you're in the Layer Panel with the correct footage loaded ie the exact same layer within the same comp as the original tracking data is kept intact within that layer's timeline properties.
When you've ensured that you have the correct layer and you're in the Layer Panel, select the appropriate tracker under the Current Track drop menu. With the correct layer selected, all the previous tracking options including target layer that were associated with the tracker are brought to the fore.
You can then add to your tracking duration, re-track parts or re-apply with different any of the 3 different x-y permutations.
BTW, it's a good idea to rename a Tracker from its default Tacker# naming convention. You do this in Timeline by selecting the layer and hitting U to display keyframed properties. Then rename the Tracker as you would rename a layer.
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