How to debug the SAPScript forms printed in Update Tasks? (When break points in OPEN_FORM don't work)

I am trying to debug a SAPScript form that I would print from transaction MIRO.

If I turn SAPScript debugging on, the debugger does not get called.

If I put a breakpoint in function module OPEN_FORM it is never reached.

I would like to debug my form, if possible.

The logic behind what is going on is a little complex. I see a lot of "BAdI" names being used in the code, but I do not have any experience with those, and would not know where to start with this problem.

The form that I am trying to print can be found in transaction NACE,

If more info is required, please ask, I do not really know what info would be helpful in this case.

[EDIT]

Steps to reproduce:

• I fill in the Invoice date and the other highlighted field. The highlighted number at the bottom is a Purchasing document, then I hit Enter

• I fill in the Amount and Quantity for the first entry (the PD must have positions, but I guess you get what's going on here)

• I Set the Correction ID to "Vendor error: reduce invoice" for the entry that i've already modified

• I set the 'Invoice Amount Acc. to Vendor' and 'Invoice Qty Acc. to Vendor' fields to greater values than those in step 2 and hit Enter.

• I check the 'Calculate tax' checkbox, and a negative value will appear in the 'Balance' field. Here it's 205,87- EUR. I fill then the 'Amount' field with the positive value '205,87' so that the document 'Balance' comes to 0.

• I hit Save in the global toolbar and then a popup appears asking me for to enter a bar code. I enter any numerical value there and hit enter. At this point I am greeted with a "windowsy" popup asking me to print the form.

Found it:

When in the debugger, go to

Settings > Change Debugger Profile / Settings

In the dialog that appears, check the checkbox "Update debugging" (2nd from the top)

Now the breakpoint placed in OPEN_FORM will break.