Captivate 8 Quiz - text box error - double shadow

I just found another error occuring with my Captivate quiz answer text boxes - upon previewing the project, when I roll my cursor over the answers the shadowing is normal the first time around:

However, if I click my Back button and return to a question and run my cursor over the answers, this happens:

The shadow doubles - you can see how the shadow is slightly thinner in width the second time around by the edge under the red circle.  This only happens on the first question, and only when I've used my back button to review the answers.  Does not happen on any of the other question slides when I use the back button to revisit them. 

Is this a bug, or is this something I can fix?