Ah, I don't understand the difference. I've tried messing with the "Interpret Footage - Main" to no avail. Also, the overflow ratio is 17:19, not 17:18. This bug only happens whilst rendering. I'm able to playback the problem spot over and over again, but not render it.
I've already looked up and tried all of the above, again, to no avail.
Thank you for posting an awesome response, but sadly I'm looking deeper and can't find the answer. Still : Anyone who can help - I would greatly appreciate it.