Custom drop down ticket field autocomplete in Guide form

Hi, we experience this behavior in the support agent workspace: in the custom drop down ticket field we can use the autocomplete fill like here:

We expected the same behavior in the Guide form but what we see is very basic and the drop down doesn't work with the autocomplete like here (drop down field from the form in the ZD Guide):

We need, for our end-user form, to offer the autocomplete feature in the drop down filed like in the support agent workspace. Rally i don't understand the different behavior for the same drop down field..