Where did you set the voltages/clocks? Claymore, Wattman?
Claymore. Wattman behaved similar: after crash Wattman restored the defaults and after that the AMD driver completely ignored anything I set in the wattman application profile or Claymore.
How about MSI Afterburner of Sapphire Trixx?
It runs with Trixx settings, but at higher power and undervolt is unstable. So no solution.