I don't know if I misconfigured the addon, but I don't see nameplates of the monsters resurrected by the Reaping affix in mythic+. The only nameplate I can see is my target.

As far as I remember those mobs have standard nameplates, so see FAQ 1 in the curse description: https://www.curseforge.com/wow/addons/kuinameplates

However, they don't seem to have any threat data. So if you have "always show nameplates" enabled already, it might be being caused by an option in KNP to fade out nameplates which aren't in combat with you.