OK, I have this thing solved now.
Having ruled out the keyframing, I went back to look into the size and presets. I found that size does matter (though as a novice, I'd be happy to understand why).
images were captured at 1280x720.
project setting was a preset of HD 1080i.
The first and only publish i made was to wmv (LAN preset, 640x480), which is less than the above. I assumed that if the entire project seemed to work in timeline view, the published output resizes everything in proportion, regardless of the resolution I select.
I've just now tested other presets at 720 and higher (flv, avi, mpeg) and all went fine; whereas anything less than 720 gave me the same behavior I was complaining about.
So what am I missing? isn't a published video with scaling/ motion paths etc. supposed to function as seen in editing mode, regardless of resolution considerations?
I thank you once more for your patience here,
L.