Tile size problem

I’m trying to make a map to use in RPG Maker VX Ace. When I have the tile size set to 32, it only fills the bottom left corner, like this:

Is there any way to fix this?

Looks like you have the map’s “grid size” set to 64x64 (or close to that). The grid is clearly larger than your tiles.

In the left “Properties” panel, you can set your map tile size to 16x16, and the map should look fine.