I’ve never used the tile map features before now, but I got it to work without too much trouble.
The first thing that comes to mind is that you might have empty space around the tile sprite. If you have an atlas, make sure that the sprites are set up in perfect grid spaces (32x32, 64x64, etc…), then you can slice the tiles in the sprite editor using “Grid by Cell Size.”
Also make sure that the “Pixels per Unit” is set to your sprite’s height/width. If you’re using a 32x32 sprite, set the pixels per unit to 32. The pixels per unit should be the same for every sprite in your project.
If all else fails, you could try importing a single tile (not an atlas) and see if the issue still occurs.
You can also link the tiles you’re using, and I can try to make them work in a project to see if I can spot the issue.