Ian,
If the breathing system is the same as on the S6, You'll find that the gases are taken from the timing chest, via the timed breather, to a drilling across the back of the crankcase halves, to exit via a port in the inner primary chaincase. In the drive side crankcase, there is another angled drilling that is an oil drain. The gases (along with the oil mist) slow down on entering the cross drilling, and deposit the majority of the oil on the walls of the drilling - this oil then settles and drains back through the other drilling into the crankcases. If the smaller drilling is blocked, the oil has no option but to flood the primary chain.
Regards,
Eddie.