If everything in the environment is configured OK, errors of this type may be transient, and resolve themselves after a few discovery cycles. However, this looks more like a persistent config issue, either with the ESXi servers, or the Balance config for these servers is confused. This may be due to things like duplicate host UUID on the servers, etc. If you delete the servers, Balance will consider the elements LOST after 7 days, and clean them up. This will take way too long.
There is not much more to troubleshoot through this forum. Please open a technical support case, they will triage and escalate to engineering as necessary.