Top half of body walking through blocks.

So there I was making an enderman farm because I just got mending on all my armour and I was literally crossing the bridge that I had made, keep in mind I had barriers blocking me from falling. Suddenly I started drowning and I looked up at my screen, I was falling into the void to my doom. There weren't any gaps in the barrier and I had tried recreating it and even a whole block (upper half of my body) I found out that I can walk through it. I don't know if it's my iPad messing up or just the excessive play time, but it has been happening frequently and it will discourage me from playing if that happens again.