AIP scanner not discovering sensitivity content

I am deploying the Purview Information Protection AIP scanner to scan an some of the on‑premises Windows file share and some network file shares that is in scope for compliance and data protection. However, the scanner is not discovering sensitive content within files stored on the share for a custom configured SIT.

The custom SIT is tested and it properly works, but the data are being reported as no matches / no sensitive content found to discover the files that may be applied with sensitivity label.

This issue is observed across one or more mapped repository paths and may be inconsistent by folder, file type or file size.  I noticed  the scanner appears “healthy” service is running, repository configured and schedules enabled.