Fixed my issue by selecting onboard graphics in Sytem Agent Configuration (vs Auto) rebooted, then reselecting Auto. All the while switching my display cables to view POSTs. In the end I was able to DISable CSM and post successfully. Profile lock ups have also gone away. Hope this helps someone.
I had the same problem on the ASUS Z170-DELUXE motherboard that purchased 2 weeks ago and with the latest BIOS. It is unfortunate that this problem is still present. Anyway the solution with CSM toggling worked for me, thanks!