[ISC.0082.9026] Undefined Object found

We just upgraded to 8.0 from 7.1 IS.

A flow service is working different in 8.

In 8, the flow service returns an error failed: ‘/xxx VV-002 [ISC.0082.9026] Undefined Object found’

Where xxx is data in the pipeline but not defined in the flow service input.

The service did not do this under 7.1.

Input to the service has “Validate input” checked. The service is invoked from another service. The required input is provided, but its the other data in the pipeline that causes the error.

The service(s) can be fixed, but I would like to understand

Has anyone had any experience with “Validate input” working differently in 8.0 vs 7.1?

Is the error valid or does this look like an issue with my environment/8.0?