serial numbers are not coppied to inspection lot

Hi ,

In our case we have a Purchse order having 50 line item of the same material( 1 qty each per line item) . After goods receipt system has created correctly 50 inspection lots  but the issue is that system has coppied the serial number for first 25 items (inspection lots)only and in rest 25 inspection lots serial number are missing. I have checked the GR serial does exist for all the 50 line items in GR document.

Need input to know  this behaviour of system.

Thanks