Drag and Drop with Auto-Submit - Success Action Not Working

I'm setting up a Drag and Drop in Captivate 2019 that should behave as follows:

1. User clicks sources to drop targets - incorrect placements snap back automatically; correct placements drop in place.

2. Once the user finally places the last source on the last drop target, a success message is displayed and the user can click anywhere to move forward.

So far I have the drop targets rejecting incorrect submissions and accepting correct ones. However, when the final source is placed, nothing happens and you don't go to the next slide.

Here are the settings for the D&D exercise:

1. On success: Go to the next slide

2. On failure: no action

3. No. of attempts: 1

4. Success caption: selected

5. Auto-submit correct answers: selected

6. On the object actions menu, each drop target is set to allow one Drag Source Type

• Accept All: Unchecked
• Count: 1
• On accept: Go back
• Action for each source type: no action

Do you think I have just have some setting that's off? Thank you in advance!