Frogs fall through floor, and suffocate on blocks with stairs underneath

I had a frog that died while I was in a different area i heard it suffocate but there was absolutely nothing that could have killed it. I copied my world and spawned a dozen or so frogs in the same area and watched repeatedly as the frogs suffocated in the floor some times after jumping, sometimes for no reason at all. my house that I had them in seemed to be the perfect test area for this particular bug because they seemed to die often.