This tutorial shows how to create a custom button UI without any Verse code in Unreal Editor for Fortnite. We had issues initially, but found that once we used an overlay instead of a canvas panel, the system worked perfectly. We decided to share what we learned as a way of helping those who have helped us.
https://dev.epicgames.com/community/learning/tutorials/4yPG/fortnite-modal-dialog-variant-create-a-custom-button-ui-without-verse-code