Either you have a defective Motherboard Thermal sensor or the sensor on the CPU is defective.
Could possibly be Asus own software causing the problem or the latest BIOS has a bug in it.
I would open a Asus Support Ticket either through email or Online Chat and see if they recommend RMAing your motherboard.
Also open a AMD Warranty ticket and see if they believe the sensor issue is due to the processor itself. You can open a Warranty ticket from here: https://www.amd.com/en/support/kb/warranty-information/rma-form