Next button won't work when base timeline is inturrupted

Hello,

I've discovered a problem that could derail a LOT of our training. We use layers a lot, and we also want to ensure that our learners can't jump ahead and skip content.  We set the player to Restricted, which is great at stopping the Next button from working until the timeline is complete.  

However, it is possible that a learner will click onto a layer before the base layer timeline has completed. This, it seems, stops the Next button from activating, even when all other layers on the slide have played out.

Is there a fix to this or am I missing something obvious?

Thanks!

Jay