Hey all ..
Putting the effects directly on the clips will fix the issue. It is definately the adjustment layer that has an issue. I at first thought it had to do with my GPU acceleration, but tests showed it didn't matter whether it was software only og GPU. When I single frame jump with arrow-keys through my adjustement layered footage, the initial render in the viewport shows the horizontal areas with no adjustment layer applied (like random chunks or blocks with no adjustment layer). After 1 second or so the viewport updates again with the complete frame calculated with adjustment layer over the whole area. - But as you've also experienced, final export suffers from the vertical "missing" areas of calculation of the adjustment layer.
Torsten