I design probably around 100 presentations per year and over the past decade or so there have been a few projects (out of 1000+) where it did not work out between me and the client. 

• The biggest one: the story was actually not that compelling. Even the best design effort can turn a poor story into a great one
• The client insisting on very remote, forced, unnatural visual analogies. 
• The client insisting on overly "spectacular" animations and graphics (1. I think they do not add anything to the story, the opposite is probably true, and 2. they are hard to do in PowerPoint).
• Not being at the core of the design process, when you are 2-3 steps away from another team that is writing the story and designing slides.

Art: Escape from the 'Luxborough Galley', John Cleveley the Elder, 1760