I had the exact same issue as this. I was running at 3.8(would boost to 3,9 sometimes) with vcore left on auto, max voltage was around 1.22, all my stress tests were good but sometimes things would randomly lock up for about 10 seconds.
I've loaded 'optimised defaults' in mobo which has my ryzen 5 1600 running at 3.4 and boosting to as high as 3.78 on 1.22 volts, but I have no lock ups.
Do you think low voltage was the cause??