Question 2 CPU Cores are not showing up

As the title says, 2 of my CPU cores are not showing up.
On device manager 6 cores are detected but task manager (and other apps) only detect 4 cores.
Anyone know how to fix it?
In Task Manager, the CPU Performance display, right click on the graph and change graph view to show Logical Processors.

Type MSConfig in Cortana search box, in Boot tab select Advanced Options and set number of processor to the total number of THREADS your processor has...if it's 6 core/12 thread enter 12 processors. Then reboot.
It only shows 8
Did you also go into MSConfig and it shows only 8 in Advanced Options? If so, then try @SamirD 's solution.

Go into control panel and delete your cpu in the hardware list. Don't restart until the last cpu is deleted. When you reboot it should find all of them this time.
I think you mean Device Manager... you can get to it through control panel or This PC properties.