Customer has an active SCCM integration that runs periodically. The logs indicate there are successful updates and inserts but when you go look at the "Most Recent Discovery" field in the CI record it hasn't been updated.
Since the records are created by the SCCM integration\transform sets and not by Discovery, the field "Most recent discovery" is not mapped by default.
You can map field "Most recent discovery" or any other field of your choice by going to:
1. Integration - Microsoft SCCM -> Data Sources -> SCCM 2016 Computer Identity -
2. Open up the transform "SCCM 2016 Computer Identity" in related links
3. Under Field Maps, click New to add a new field to this transform
4. Select the target field "Most recent discovery" and a source field (for example Updated) and submit