Weird Terrain Bug When Doing This

Step 1. I setup a server for 20 player's
Step 2. Made Myself an Op on the server with permissions to go over the player limit
Step 3. Loaded The Server's World
Step 4. Logged Off the server and set the player limit to 0
Step 5. I logged back on and the terrain Changed every time i did these steps

Look at the pictures Below, This is the same World