eLearning [EXIT] course button with a prompt not working.....

An eLearning customer insisted on adding an [EXIT] button to the player with an intermediate prompt to let the learner [cancel] or [exit course] after selecting [EXIT].  They also want to ensure that the learner can return to the last lesson slide viewed if they resume the course.

To achieve these goals, I implemented a lightbox technique to display an exit prompt following selection of the [EXIT] button.
[cancel] works fine with a 'close lightbox' trigger.
However the [exit course] button required two triggers to accomplish the goals, first  a 'close lightbox' trigger, followed by an 'exit course' trigger - both triggers are initiated from the user clicking once on the [exit course] button.

The customer's LMS seems to be concatenating the dual [exit course] button trigger technique - only the first trigger  'close lightbox' is executed, then.....nothing (possibly due to the exit course lightbox containing the 2nd trigger already being closed?)

Without the first 'close lightbox' trigger, when the course is resumed, it displays the exit course lightbox (as the 'last slide' viewed). Not cool.

Storyline is certainly sophisticated enough to handle a routine as simple as this exit course prompt, however I am a mere mortal novice using it's vast potential and just can't...quite...think...outside of the box I've created.

Suggestions??? Thanks!