Magento 1.9.3.9 Credit Memo - Update Qty Button not working

[GTLTD]

HELP! In our Magento, I've just gone to process a refund, and the update qty button is not working, it's greyed out and cannot be clicked? Anyone have any ideas why?

Help gratefully received!

[Damian Culotta]

Hi @GTLTD,

Can you share the Creditmemo details (removing your customer data)?