Disappearing Custom Properties for Number Shape add-on modified-sh

[papapatent]

I took one of the text boxes created by the text tool that has been modified
by the "Number Shapes" add-on and added an "HidePageNumber" boolean value
that toggles whether the page number should be shown. Thus, I have four
custom properties:

1. Prop.ShapeNumber
2. Prop.ShapeNumberText
3. Prop.HideShapeNumber
4. Prop.HidePageNumber <-- I added this

I also changed the formula in the Text Fields to be:

=IF(Prop.HideShapeNumber=0,IF(Prop.HidePageNumber=0,IF(Prop.ShapeNumber<10,Prop.ShapeNumberText&PAGENUMBER()&"0"&Prop.ShapeNumber,Prop.ShapeNumberText&PAGENUMBER()&Prop.ShapeNumber),IF(Prop.ShapeNumber<10,Prop.ShapeNumberText&"0"&Prop.ShapeNumber,Prop.ShapeNumberText&Prop.ShapeNumber)),"")

The if Prop.ShapeNumber<10 is supposed to check whether the shape number is
below two digits, and add a leading zero "0" if needed as I want all the
shape numbers to be from 00-99.

I left the Format to be FIELDPICTURE(37).

I then created a Master Shape using the shape and named the master "Ref. No.
w-Page." However, when I drag it onto a page and type a number into the
Shape Number using Custom Properties, the first three custom properties (1.
Prop.ShapeNumber, 2. Prop.ShapeNumberText and 3. Prop.HideShapeNumber)
dissappears and I get a "#REF!" displayed in the text box.

Is my formula incorrect and causing something to break?