Tile sizes can differ between maps and tilesets. For the map, it’s the area occupied by the tile, not including the extra bits that stick out, and it looks like you’ve entered this correctly. For the tileset, it’s the bounding box of the entire tile, the rectangle size that the tilesheet needs to be cut up into.
Although you put the grid width and height, notice how in the image properties, the tile height is still incorrect at 28. This is what’s causing the issue. You need to change that to 48. You can edit the value by clicking the “Edit” button on the Image property.