Kevin, you will need to go into MES, create a app studio layer, need to redirect button click event to open “End Activity” app and add your layer name there. Unfortunately, this is the work around for now.
You can find some help here too:
https://www.epiusers.help/t/issue-with-creating-a-drop-down-menu-in-kinetic-data-collection-using-application-studio/116702/8?u=itsme