Is it correct to say that the Default Value in the Custom Fields only work if Store Value is unticked?

not correct

Interesting I can't make it work if the box is unticked

The default value is set during record creation/initialization. So once the record is saved or field value is changed it will not set the default value back Furthermore if the field is dependent upon other values (like subsidiary) it cannot be set until the subsidiary is defined so when initialized there is no value to select. Thus default value cannot work in that case

Mine is literally just {discountrate} because it's not exposed in saved searches. Doesn't work unless I untick the Store Value box

So you are trying to set the value of a custom field when someone enters the {discountrate}?

If you set a field to store value this means it will appear in saved searches and I believe will be a value in the database. If you don’t set to store it will be calculated only on the transaction or records when they are viewed. So if you want to use it in saved searches you need to store it.

@MGBC does not have to be right away. It just does not populate after field edit or upon save when Store Value is ticked. Had to create a WF to store the value