10.10.4 broke my DisplayPort -help

Late Mac Mini, 1TB fusion, 16GB Ram, hooked to 2 identical ASUS displays, one via HDMI, the other via DisplayPort. I have never had issues until I upgraded to 10.10.4 - then the DisplayPort immediately stopped working. Nothing else changed. I've tried resetting PRAM, booting in safe mode, using a Guest User, and cleaning out any unnecessary login items within Users & Groups. In short - I've tried everything I can think - it simply won't recognize the display.

This has to be software driven. Am I out of luck? Wait for 10.10.5 or 10.11?