So there has been similar bugs but nothing that fits this bug exactly, so basically blocks are disappearing in small chunks. I been playing on this world for years and its only been happening more recently, i built this watchtower and a few days later when i went to place/look at the flag on it, the roof and flags were gone. Then it happened to my mob farm and now today to my house roof. I was using i farm that involves switching a nether portal on and off rapidly and it makes my game run slower(more choppy) and i afk next to it. Its not that laggy ps4 is just naturally laggy and i have alot of items in my chests which just might add to it but it definitely was caused from the nether portal, after i go to my house, my roof was missing like a creeper exploded but it was a longer hole and didnt effect downwards. I searched a little bit and someone said it could be chunk corruption but i highly doubt it since its happened 3 times in different chunks. It didnt effect and chests or anything yet but so far its been player placed blocks only. I have gotten an error type thing for minecraft not being able to save to the online storage so maybe that could be it but i think it happened before it gave me that message and it shouldn't be a problem if it can't upload to cloud since its saved on the system. Im on ps4 bedrock and on version 2.18.