Tab Engage Interaction and "Next Slide" button

I have created a simple tab engage interaction and have set up the properties so that students have to view all tabs (there are 5)  before the "Next slide" button appears in the upper right and allows them to advance to the next page in the course.

However, once students have selected the last tab, and the "Next Slide" button appears, after a few seconds, the slide advances on its own to the next page in the course. The student doesn't have the control to click "Next Slide" -- even though the "Next slide" button does appear.

I cannot seem to locate what is causing this to happen.  It is as if the interaction has been programmed to advance after the last tab -- without requiring the student to click the "Next Slide" tab.

Any ideas on what is causing this to happen?