Haha, the platform did not disappears, it falls down (I think that the first person camera didn't allow the player to see that sometimes).
Did you check the level surroundings? There was a panel telling that Shift is to Sprint, and then if you Sprint and Jump you can get to the next platform.
In my opinion, the fun part is that there's no "right" way to complete each level, but you may improve your score by playing differently.
Thanks for the feedback! I really appreciate it!