HWmonitor misread your clock speed, it is fairly common with RAM speeds and core clock speeds. One would need exotic cooling to reach 5.5GHz on any Ryzen CPU. The maximum clock that I have seen or read about people achieving using XFR2 and Precision Boost Overdrive (enabled with stock settings) is 4.4GHz. The average all core overclock is slightly lower ~4.2Ghz-4.3Ghz (overclockers.net, HWbot, Reddit, AMD forum).
Adding the average column to HWmonitor will give you a better idea of what clocks you are achieving during gaming or benchmarking. If HWmonitor does not offer a 4th column (average) you could use HWinfo64. This is a similar program to HWmonitor but it offers more readings and a average column (HWinfo64 can also give misreads)