A new KCS article was published: KM00445964
When a Field is set to not Display, cannot use User Interface (UI) Rules to make Visible because the element does not exist
When using UI Rules in Project and Portfolio Management (PPM), the "setFieldVisible(true)" will only work if the Field is set to "Display:Yes" in the Status Dependencies tab.
This is because if the Status Dependency is set to "Display: No", the Field basically does not exist for the Rules, so no Rule can be run on it.
In order to circumvent this behavior (namely wanting to set a Field to not be Visible at some point and then set it to Visible again without playing with Status Dependencies), create a Rule, on Page Load for example, in which can use the parameter "setFieldVisible(false)". This would then make sure that the Field is always false on every Page Load unless another Rule sets it to Visible.
Both setFieldEditable and setFieldRequired will also behave the same if the Status Dependency of the Field is set to "Display:No". If it is set to "Display:Yes", will work as expected.