No the script works fine, it’s really a clunky update with Blender itself.
Thanks for your step by step images – very helpful.
I can see that you have changed the ‘Default Value’ correctly.
However, when you edit the property, there is no longer a way to change the ‘Current Value’ in that pop up menu.
(This really is an oversight by the devs in my opinion).
When you click OK, you will probably see that the actual value is still 1.0.
You can type the value in there again…..or because you have already set the default, you can just hover your mouse and press backspace.
That is the shortcut to return any value back to its default.
Backspace is faster.