Cathleen Fisher

It seems to be related to where the player comes out of a nether portal. You can "fix" the map by picking it up and running around to fill it in again. However, when you log out and log back in, the map reverts back to being all black.

Update:
Without touching the maps, I ran away to meet another member. We each took screenshots of my maps and they were not the same on each other's screen. Also, the map changed for me from when I had previously looked at it as you can see in the second picture.
We left and I came right back a minute later and my maps changed again.

I have a Samsung Galaxy S7 and has started overheating while i play Minecraft since Render Dragon.  It gets hot enough that my phone gives me a warning that Minecraft is causing the issue and then it shuts down the app.

I do not wish to repeat this for a photo unless you'd like to buy me a new phone 😛