DEMO: Hide player Prev/Next buttons on Quiz Review SL2. Update Sept 2018: SL360 demo file attached.

I've just had my own experience with the Review navigation complication in storyline, and having spent a lot of time sorting through posts here I wanted to share some of my own discoveries for others who might end up here after exhausting searching, as I did. For reference, I'm using Storyline ver 3.5.

My goal was to entirely avoid using the player and create custom navigation usable from start to finish of the project, including quiz and review. The quiz is set up with only Prev/Next navigation and a single submit on a Review page at the end. The project also allows the user to freely navigate through questions, and Flag questions for revisiting. Obviously, introducing a completely different set of navigation buttons to the user at the very end of the project was not desirable.

After following the suggestion to enable the buttons from slide properties and disable them via trigger at timeline start, my result was each slide still loading with the player space reserved and the player Previous/Next buttons visible for a split second before changing state to Hidden. 

I was about to give up when I discovered that enabling Prev/Next and applying the Hide triggers to the slide Master, not the slide itself, eliminated this loading issue. Previously, my Master slide was set to disable these buttons as I never use them.

After taking this approach, I could then disable the buttons on the Quiz slides from the properties and not have to worry about applying the additional 2 triggers to hide them on each slide.