Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.
Hey mate, I'm not much help but I've got a VE Series 2 2011 wagon with 160000 on the clock and it's just started doing almost exactly the same thing although mine seems to be only while driving in traffic and starts happening after about 1 hour. When I turn the key just after it happens I get no response at all until I wait about 15 minutes and then it starts no problem and off I go until it happens again in anywhere from 30 seconds to not at all.
Took it to the mechanic he says that he's checked it over and can't diagnose as there are no obvious faults and no error codes.
I was about to start replacing parts as a process of elimination, would start with fuel pump and filter and perhaps relays but your post makes me very doubtful on where to begin.
I'm wondering if anyone else has had this problem and if they found a solution.
Please keep me posted on how you go and i'll do the same.
Cheers