This is the part of the code:
if ((rift != null)&&(rift.isVisible())){
rift.interact("Exit-through");}
This is the location, camera angle:
The problem: Rift returns as visible, but doesn't interact. Occurs at exactly these conditions. Easy to reproduce, by walking away from nature rift, then stopping at spot. For some reason if you walk towards the nature rift and you stop there, then it will interact.