Hi Wes,
It is like you forecasted - for dual gpu systems the Intel driver makes the difference in these days. I downloaded (manually) the newest Intel driver that was available yesterday. Installed - and the crashes with 13.1 are gone.
I am not sure if I have maximum perfomance. The rig seems to need to render where Premiere 2018 (and 2016 etc.) did not, although the Nvidia monitor cleary shows that GeForce 1060 is doing the work. But I am using very old Nividia drivers right now which I downgraded to in search for a remedy.
Thanks a lot, and I will keep you updated.
Ludwig