Hey Emsegal,
You can either try to re-generate the table, or you can contact your business consultant and we will look into this for you.
If you want to regenerate the table, follow the steps below.
First confirm the dropdown is assigned a table, do this buy editing the screen and looking into the properties of the dropdown in question. If the dropdown is not assigned a table, select a table and publish the screen. Test it out and see if it works now.
If that did not fix the problem, or it was assigned a table, follow the steps below;
Go to Customize > Tables / Fields > one you are looking at the list of tables, loca
te the table that this dropdown menu is linked to and select "Edit Fields". Once this pop up loads, click "Finished Editing Fields".
Try the screen again. If this fails, contact your business consultant.