Can you tell me what Access build number you are using?

Ms access form calculation updating table
So I'm somewhat new to access 2013, anyways, I've created a form in access 2013 based directly off a table, so no queries involved if that matters, and what I'm trying to do is just have a text box that updates the total value of 3 different fields as they're entered.
right now it's just a plain-text box, the control source is "=[Search Cost] [Update Cost] [Copy Cost]", and if I close the form entirely and reopen the record it updates the text box with the total for all three, but the customer wants it to update in real time. I just tried your scenario in Access 2013 on a simple form and it updated for me in real time as I entered values.
This Visual How To shows how to add support for denormalizing the Orders and Orders Details tables in the Northwind sample database, adding a column to the Orders table that maintains the total amount purchased in the order.
Although denormalizing data is generally not optimal behavior, it can increase performance when you create reports.
However, that was because each of the three fields values had a Default Value of 0 in my test table.
So I suspect this is not updating for you in real time because one or more of those values is null while you are entering data in the form.
Let's say we have a database that tracks applicants and case workers, and when cases are assigned, signed out, and closed.
Following this example, let's say we would like to automate the date for when a case is received.
In addition, the Northwind sample database includes data in the Order Details table, and you need some way to roll up that data and initialize the Order Total field in the Orders table─this means that you must create a separate data macro that you can call to perform the initialization of the Order Total field.