Shape Identity

I'm trying to put a custom property "ShapeID" into every shape on my
page such that each one contains its unique shape identity.

To do this I am adding a custom property row to the Master Shape and
using =ID() in the value field. It applies this change to every shape
instance on my page as expected, but does not re-evaluate the formula
for each shape instance. If I go into a single shape and enter the
formula, it evaluates the formula as expected.

Is there any way I can force each instance of the shape to re-evaluate
its shape***?

Thanks.

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