In the Windows operation system, the "wmic.exe bios get serialnumber" command gets the same value as K1000 Inventory page displays.
For some models of Lenovo, it inputs the Serial Number in a different place instead of the place where the "wmic.exe bios get serialnumber" command is looking for.
From Lenovo forums, they suggested these two commands for getting Serial Number,
"wmic.exe bios get serialnumber" and "wmic.exe csproduct get identifyingnumber".
Please try this command "wmic.exe csproduct get identifyingnumber" in the system to see if it can get the same Serial Number value as the label on the chassis shows.
Then, use Custom Inventory Rule to report the value to the K1000. Please refer to K1000 Admin Guide on writing Custom Inventory Rule.