Troubleshooting: Serial Numbers are not shown in detail in Invoice

Question : In Invoice : I-000014 the serial numbers are shown in detail (A0001, A0002, A0003), but in I-000015 it just shown in a range (B0001 -> B0003). Why? How to make it to show in detail?

Version : 1.8 / 1.9 / 2.0

Invoice I-0000014:

Invoice I-000015:

Possible Reason :

Upon creating Invoice I-000015, user has directly keyed in the serial number in Starting S/N and Ending S/N column as below.

When preview invoice the serial numbers will be shown as a range.

Solution :

1) Delete the item detail line for I-000015 and Save.

2) Edit again the Invoice to add back the Item b and key in/scan the serial numbers one by one, or double click (to choose) the Serial Number from the Available Serial Numbers, then Save the Invoice.