Help - No Next Button on slides

I have a really large piece of e-learning which was originally built with storyline 2 and I have now upgraded to storyline 3 

I have the work files and open them and upgrade the package to storyline 3, however when published or previewed no slide shows the default next or previous buttons.  Obviously they did when I first created this and published it in Storyline 2

I've checked the slides, next and previous check boxes are still checked, nothing in the player to indicate why they aren't showing.

I've asked a colleague to load on her Storyline 3 and she has the same issue

Help much appreciated thank you