A trigger that performs an action when an object is dragged over or dropped on another object won't work if the target object has no fill or line color (i.e., it's invisible).
To correct it, use either of these options:
- Add a fill collor to the target object and set its transparency to 100%.
- Use a hotspot instead of an invisible shape for the target object.
Note: This issue only happens with drag triggers and drop triggers. Objects that have no fill or line color can still be used as targets in drag-and-drop interactions.