Empty search box options

I am having some issues to understand why the dropdown of the search is not being proper filled. I have a form with a lot of sub-tabs (relations). For those relations I can see  the search box well filled. However in one of those relations I have a button that when I click I will see a popup with  a form and a relation. All data is well showed less in the search box  of that search that it's not well filled. One of my ideas It was also trigger the event to fill that drop . Can you give me some tips to have also the search proper filled? Thank you!