Your are not able to activate buttons/levers with tools in your hand while sneaking. I know, if you hold a block in your hand it should be placed, but that are tools. If you want to hit a button or lever while at example you are on ladders, you can't do it, because you have to sneak to stay at the same spot.
(I really hope that is not a duplicate, I found nothing... :/)
Duplicate of MC-4565, please use the search function to see if your bug has already been submitted. Currently over 51% of tickets are being closed as duplicate.