menu_array can't detect user selection

[TheIronGolem]

In a form I've made, I've hooked up a menu_array element to a component I wrote that includes the UserSelect component. XML for the element is:

<menu_array
  field="usrSelect"
  array="usrArray">
</menu_array>

This is pretty much verbatim from the sample file visual.dat, and it does correctly display the array options when I click on the menu:

But it doesn't seem like the user selection is "sticking"; after I click on an option the menu blanks out and the value of usrIndex does not change:

I feel like I'm missing something about how to communicate the user's choice to the menu_array element.

 

[Aaron]

What is the usrIndxFix field value? Could be running afoul of a fixup script we have.

 

[TheIronGolem]

usrIndxFix is remaining at 0, regardless of which option I try to select.