https://www.cisco.com/c/en/us/support/docs/optical-networking/optical-networking/220373-troubleshoot-qsfp28-not-detected-in-in.html
Troubleshoot "QSFP28 not detected in inventory" - NCS1004 Software Release 711 and 721 - Cisco
This document describes how to identify inventory discrepancies of optics in NCS1004 and offers a solution to address the issue.