I guess you checked the interface if everything is OK in the PI point configuration?
On OPC interface node, request you to check below
1) Connectivity to PI server from Interface node
2) Security i.e PI Trust or API between PI server and interface node.
3) PI Tag security configuration - ptsecurity and data security
4) Using OPC client tool check if the point is updated in the source i.e. instrument tag=item id (OPC) server has a good value
5) Check Interface UnitInt section for any specific configuration
6) Check Scan class and point source mapping against PI and PI OPC Interface
7) Check if buffering is configured. If yes, check if buffer subsystem logon id has permission on PI data archive database i.e. PI POINT.
8) Please make sure that OPC instrument ID(item id) matches with PI Tag instrument tag
9) Start PI OPC interface in interactive mode and check for errors
Did you have a look at the SDK logs on interface startup? Here is the KB with more information on how to retrieve the SDK logs:
If you don't see any errors or warnings, I would look for the line in the messages that says how many points were loaded by the interface. I have a feeling that either your Point Source or Interface ID (location1) in your PI Point configuration doesn't match that of the interface.
Hope this helps,