I completed upgrading our vCenter Server appliance to 6.7U3. After running into a number of issues doing that, I've finally got everything back normal. The goal was to add new host hardware we have, which we installed ESXi 6.7 on. Since we were running VCSA 6.5, I upgraded that to be able to create a new cluster for the new hosts to be managed by the 6.7 VCSA.
I created the new cluster, enabled DRS, enabled HA, then enabled and set EVC to the highest on the list (Intel Merom). We're using hosts with Intel Xeon Gold 6143 CPUs. I followed the wizard for adding new hosts, it seemed to connect and identify them with no issues, but when I start the adding by clicking finish, it fails immediately with the following error message: