The shop did another test ride today and again oil is puking out of the rear breather. The shop thought they had fixed the issue until it dumped right as they were pulling in from the test ride. The manager said their most experienced tech is stumped. They are working with Zipper's to figure this out.

 

Leads me to think possible oil pressure issue. I know it seems strange to be exiting the rear only but the thought of fluids following the path of least resistance could be in play. Possibly.

I would put an oil pressure gauge on it an run it. If high or fluctuating look at that check vavle just inside the oil filter mount possible sticking.