Try raising a ticket with netapp support. Found this kb, it may not be your issue but check it out.
https://kb.netapp.com/mgmt/SnapCenter/SCV_discovery_job_fails_with_NullPointerException_due_to_connection_timeout
Question : Is the vCenter server part of the same Resource Group as other VMs ? b'cos SCV could loose connection to vCenter (possibly because of a snapshot being taken of the vCenter VM). Have a separate RG with different schedule for vCenter VM. Good luck.