Thought I seen it all, on system wake up from hibernate my CPU randomly gets stuck on 5.5x multipler even if all threads get saturated and hit 100% usage the CPU doesn't go over 550MHz.
I did few quick searches on google and did not find anything similar. In my case ALL of the cores won't go above 5.5x multiplier, the workaround is to restart the system and avoid hibernating. I got into habit of hibernating the system to workaround the infamous NVMe disk drop on wakeup from sleep (that I eventually fixed. There's a separate thread I made for that)
@ElGranPC, good tip, I will take a look at Windows power plan next time the CPU multiplier gets stuck. For reference my system was using "GameTurbo (High Performance)" plan which seems to stem from GameFirst VI application, at some point it applied that plan. I'm not using GameFirst VI anymore as it conflicts with VPN software. I'm back to "Balanced" plan for now with couple tweaks on top like no HDD sleep.