Any chance you initially added the host to vCenter with firstname.lastname@example.org or some other account than root?
I ask as the logs you posted keep stating 'Throw vim.fault.NoPermission' etc.
When I initially added the ESXi host, I have seen that the blank for username was filled with "email@example.com"(before I fill in the blank with "root").
I first deleted "firstname.lastname@example.org", then entered "root" as username.
The host was successfully added.
About no permission error, I wonder if the username value was "null" at that time.
I attach why I thought such a thing from the log(though I cannot determine it is related to this issue or not..).