Chunk resets back to before update.

I have recently been building some paths around my base in the game, and I noticed that in a particular area I was replacing, the blocks were coming back after I saved and quit and reopened the world.
I had a wood path before the snapshot update that I wanted to replace with something that looked better. After logging out and back in, I noticed that the replacing path was removed and the old one was there again.
I've attached two pictures of the bug, because I don't know how to replicate a chunk error.
I apologize for not giving any better description as to what is happening, but you can clearly see where the chunk error is. I put some blocks down and saved and quit, then came back, and the chunk reset.
Thank you for your time.