Try Reseting your bios settings to default, do the same for RyzenMaster if you've made any changes there recently (do it anyway even if you didnt, just in case) then check cpu-z again.
nyks, the most likely cause of this, seen many times, is not installing a fresh copy of Windows after changing the processor. Enjoy, John.
I just install Windows it shows me all cores, but when i select from “Ryzen Master” a profile “Gaming mode” it turns back to 3 cores
Dont use gaming mode, it doesnt really help much in gaming scenarios and in some cases your ending up losing performance due the lower core/thread cound. Also, stop messing with RyzenMaster settings unless your sure of what your doing or want to do some very specific tweaks to your CPU.
If you've already got gaming mode enable in RyzenMaster, reset all settings to default and restart your PC and check again.