Multiple symptoms as a result of service account password issues.
VCF Diagnostic Tool for SDDC Manager shows:
SDDC 5.2.x
In most cases, this is due to a mismatch for the password of the account between the SDDC database and the target vCenter Server service account. See vCenter SDDC Service Accounts show disconnected in SDDC Manager UI
Synchronize the passwords and remediate: vCenter SDDC Service Accounts show disconnected in SDDC Manager UI