I think this may be a bug in Armoury Crate. When I was troubleshooting a potential issue with the 3080, I observed the same behavior.
I plugged one monitor into the motherboard display port connector and one into the 3080. In this configuration, Armoury Crate only reported 1 core of the CPU and only 1 fan header. When I connected both monitors to the 3080, Armoury Crate started reporting the correct information again. I just tested again and see the same behavior.
I uninstalled using the instructions, which were excellent, and also reinstalled Windows from scratch a couple of times.
GPU: EVGA 3080 Ti FTW3 Ultra
Mobo: Asus ROG z490-i Gaming
CPU: Intel i7-10700K
Edit 1 - the same behavior occurs when only plugged into the mobo via display port. My 3080 is still in the system but I will check again when I pull it tomorrow.
Edit 2 - When I removed the GPU, the CPU core and fan information populate correctly in Armoury Crate with display port connection on mobo.