Listbox allow only one option

[BautistaC888]

Hello,

I created a listbox but the user needs to pick only one option.
How can you limit the number of options possible. 

I share an example.

Thank you

[PhilipMannering]

The simple solution would be to just use a DropDown.

[BautistaC888]

I tried with a dropdown but its not updating.
What is the error?

Thank you

[PhilipMannering · Accepted solution]

This really isn't as obvious as it should be... but I think I found a way.

The trick was to select field-value="unknown"...don't ask me why.