Hi Bob and welcome to the forum.
So far as I know that field property is not something with any complex states. It has been around for a long time so should be stable and I don't have a problem here when I run a quick test.
So that suggests either that you have found an interesting anomaly or things in your model are not quite as you see them.
Are you able to change the radio button from one setting to the other yet not see the effect or can you see the effect but it is just not persistent when the model is closed and re-opened?
I suppose I should start with the basic question for completeness of analysis: Are you sure that the field(s) you are working with are indeed the ones you think you are working with and that they are empty?
I don't mean that to sound like an insulting question - I think we all have times when things that appear obvious and are not considered to be worth checking turn out to be the source of a problem. I know I have such moments, usually when I have started with question 3 of the check list rather than question 1.
Is this a traditional model or are you using Linked Objects?
There are probably other questions I should be asking but right now they are not coming to mind. So let's start with those.
V11.5 (Pro): Windows 7
V9, V10.5 (Pro): Windows 7
V8 Pro: Windows XP SP2
Earlier versions "archived" as machines died ...