I have noticed the same issue on my iCue after the 4.16 update. As of 4.17.244, I still have the same issue on my Dark Hero, where temps 1 and 2 show a usually consistent 216 C but there are intermittent momentary drops, see screenshot.
Specs
Win 10 20H2
AMD Ryzen 9 3950x
Asus C8 Dark Hero BIOS 3801
64 GB Vengeance RGB Pro (16GB x 4)