Incomplete shadows with new Compositing Engine

Shadows (Layer fx) are cut off in straight blocks. Not at all zoom levels. Turn on Legacy Compositing 'solves' the problem. Seems that the new engine is not fail safe yet.
Happens with big files. 
(MacPro / nVidia Quadro 4000)
The shadow distance also varies with the compositing engine (see pics).

New Engine:


Legacy: