On my form, I couldn’t get it to fire no matter what. So I added several diagnostic test fields, and discovered what is either a bug, or an undocumented feature that I don’t know how to properly use.
gform_price_changehooks DO fire if a change is made in a product field of type: Dropdown, Radio Button, or User Defined Price
gform_price_changehooks NEVER fire if the value of a Calculated product field changes (due to every set of factors I have yet to devise.)
QUESTION: how do I get gform_price_change to pay attention to Calculated product field values? (Or, what workaround might you suggest?)