In world Composition, I have one sub-level that stretches over every other sub-level?

I set all 88 tiles to be the exact same size in World Composition. I have all the sub-levels position where I want them, but after sculpting a sub-level or adding terrain, I get this image (attached) in the World Composition tab. All other sub-levels line up and size is not changed in View Port. Please help me understand what is going on??

Here is what WC looks like when all sub-levels are made visable:

I know this is really really late. You may have solved this by now.

That blue and white tile you can see, looks like your water plane and skydome.
If they are within your persistent level, then they should™ be hidden in the world composition panel.

However, if they are contained within another level (an atmosphere level or something) then they wont be hidden in the world compositor.

You will need to set the atmosphere level as the active level, then open the “Level Details” panel and tick “Hide in Tile View”.

I hope this helps you and any others that stumble upon this.

EDIT: It looks like the second image you are showing has two copies of the skydome and water.

Exactly, you would want to have your skysphere, Sunlight, Skylight, Water level, etc. (everything that should be visible from all world cells ) in your persistant level, not a sub level.
Persistant means it’s always loaded and your loaded sub levels are added to it.

Level bounds are automaticaly stretched (unless you deactivate the option) to fit the objetcs which are in your current sub level. So if you move an object from your current level far from this leve tile, your level bounds will be streched all over your world.

Remember to always set the level as current level when you add object to it.
If you need to move an object from a level to the current level, select it and use “Control+M” shortkey