Search orders via postcode for multiple orders doesn’t always show orders

So I have to check if people have put in multiple orders within the same week so I can post them together. I do this by searching the orders via postcode, then box their multiple orders to send. However occasionally this doesn’t work, it did use to work 100% of the time. When this happens, it won’t even find the order for the postcode I’m searching.

Any help would be great. Thank you.