When you close a register, in Sell in the Magpie app or on its page in Store › In person, you enter the cash counted. When it is not the cash expected, Why is the cash different? appears and needs an answer: the message says how much more or less cash was counted, and the register stays open until you give a reason. Older versions of the Magpie app show that message too. When the count matches, no reason is asked for or kept, and the optional Note field is gone.
The reason is shown with the count as Note at closing. A register's Cash refunds have a Reason column only when one of them has a reason.