Summary says it all – Can't open chests/access furnaces/hoppers/etc. while crouching. Also cannot scroll hotbar while crouched. 

I just got a new computer (macbook pro) and discovered the inability to crouch and perform other functions, such as access furnaces, hoppers, chest, pretty much anything with an inventory. I noticed it while I was on an ladder trying to reach up to access a chest and hopper. In addition, while placing blocks on an edge and in the crouch position, I could not scroll in my hotbar to access my tools to break the blocks.