this visual is an art form of itself very nice. it appears the track has shifted in one or two keyframes and this is why you see lines. this is the attach point keyframe that has shifted. you have cropped your screen so this is not so clear. but there's something you wrote that is a cause for concern:
choose to track "position" and "rotation" and then start to track my composition frame by frame repositioning manually the track points
if you do that that frame by frame you are almost guaranteed to get a jittery track. you should help the tracker do it's thing and adjust the options to make it work better for you. rarely do you have to manually adjust the track point. can we see the footage so we can give you maybe better workflow for this?
thanx for your response Roei.. those lines appear when and while i drag the track point.. I found out that this occurs when im fully zoomed in. when i zoom out (just a click before full zoom) the problem does not occur...
this is very strange.
exact Ae version numbers?
Exact Os version numbers?
ΑΕ v 13.0.2
thought of updating to AE CC 2017, so i gave it a try to see if the problem exists in that version too.. its actually there but it behaves a bit different. this time the preview screen blacks out when im fully zoomed to Track point 2.. only in track point 2, not in track point 1 and the same applies with AE 13.0.2.. Track point 1 is ok in both versions