After changing the password expiration days from 180 to 90 without rotating the password for longer that the 90 day period you are setting will cause the root and service account to become disconnected in password manager in SDDC Manager.
VCF 5.x
Passwords had not been rotated on ESXi hosts in 90+ days so when lowering the expiration days from 180 where they were still valid to 90 where they are expired caused the accounts to disconnect on SDDC Manager.
The resolution would be to Rotate ALL ESXi passwords before changing the password expiration value.
Workaround: