OPCUaConnection Error with Kepware

We just upgraded to 7.7.6 last week. We are using a Kepware OPC connection to DeltaV. Yesterday we had the following error which prevented all data from displaying.

ERROR [OpcUaConnection[KepwareOPC] ] [19:23:33,246]: Read service call could not be completed.
StatusCode[Severity=Bad, Subcode=Bad_SessionIdInvalid]: ServiceFault: StatusCode[Severity=Bad, Subcode=Bad_SessionIdInvalid]

We had to stop and restart the OPC connection and it fixed the issue. A couple of questions: 1) What is the root cause of this? , 2) Is there a service we can monitor to see if we get OPC issues

We have had a few OPC issues recently, mostly when we restart DeltaV. We have found we need to force restart the OPC connection. This error is different however in that there was no maintenance on Delta