This is NetTalk 7.34. I attempted to re-create the problem with example 21, but the refresh button worked fine there. It turns out that the problem is triggered by including a form (containing two other forms with some display fields) on the same form as the button. It doesn't matter if the form is on another tab. If I place the form below the button (in the form fields list) it works fine, but if I put it above it does not.
I suppose I should not really attempt to "design" the layout using multiple forms, but rather update my CSS knowledge and use DIV to place things where I want them.