I downloaded engine version 4.18, created a new First Person BP project, created a widget that is draggable, created a widget used for visual, set up the drag operation in the draggable widget and played the game.
EDIT:
I just verified the bug once again. I created a new FP BP project on version 4.17, and it works as it should. After converting the project to 4.18 OR creating a brand new project once again, the issue starts occuring.