Can I use the calculation field on Create New Post action


I’m using a calculation field on a Creat New Post action. I fill the calculation with the expression {quantity} * {unitprice}* {tax}. It show the correct value on the form, but what should I fill in the calculation filed value? I let it blank and it is not saving anything on the respective ACF field (subtotal) in the new post created.

Should I use a hidden field? How can I pass the calculation for that hidden field?

I try using the {brf_form_calculation:subtotal} but it shows

Thank you for your help in advance.

Ignore this post. I was trying with a calculation field disabled. I enable it and it work fine as a normal field. Sorry!