When my son (also on Android) logged into a world on my android phone, blocks were behaving oddly.  If he touched them they changed, such as oak planks transforming into pistons.  We tried shutting down the app, shutting down both devices, and clearing caches.  The glitch persisted.  It did not affect any of his locally saved worlds.  He made a short video of what was happening, https://youtu.be/KapRGIvmJn8

We tested the limits of this bug a bit.  It happens in every world of mine that he's willing to join, newly created as well as saved worlds he has previously played normally in.  When he attempts to break a glitched block, it initially breaks at the speed of the original block, then before it breaks changes back to undamaged state and breaks at the speed of the new block. It drops the drop of the original block. My gameplay remains completely normal.  Attached is a photo of him standing in grass which to him was a slanted powered rail.

When I join a world on his device I end up glitched and blocks change to different things.  For example, oak planks appear to be dripstone and grass turns to green glazed terra cotta. His gameplay is completely normal.  Attached is an image of the changed blocks.

This is fun for now but It means we can't play a normal minecraft game together on either device.  Oddly enough gameplay was completely normal last night when we defeated the Ender dragon for the first time.