When crouching and building directly next to the block your on sometimes the block you wanna place goes on top of the block your on not besides it. I've done some testing and it only happens when playing on a server game such as bedwars or skywars. It doesn't happen when playing in your own world. This also really affects skyblock as that's the way you build out your island. I've seen that this issue happed on Xbox but was resolved in 2018. Seen in the photo is how the block is placed witch causes you to fall.