Its not everytime, but every now and then when I open a chest the loot will fall under it and be completely unobtainable. Luckily it hasn't happened to any legendaries or uniques yet, but I know my luck.

I have a screenshot of one time when it happened but I'm not sure how to post it here.

EDIT: After having it happen a few more times, it seems to only happen to cursed chests in expeditions