In WM, serial numbers are not maintained except through the HU within WM. LQ02 being a WM initiated process would not look at serial numbers.
Whereas in MB1B using an outbound delivery, the serial number profile for the material is recognized based on your profile settings; thus, the delivery note itself would require serial numbers to be entered if so defined. Since you are using Deliveries for outbound shipments, it is safe to assume the profile is defined as such.
Check your HU to see if the serial number is defined within. If this is the case and the U is not changed in the TP, the serial number should remain as reportable.