Pink square appearing in tilemap when a tile is missing

Repro:
1- Open project in attachment.
2- Open scene 'PinkSquare'. You should see that a pink square in the tilemap.
3- Open Tile Palette.
4- replace tile at the center of the square. Everything should now render properly.

I did a bunch of operations when creating this tilemap and I think I ended up deleting a tile in the process. I don't think a missing tile should affect neighbouring tiles though.

Reproduced: 2017.2.0b9, 2017.3a5 (e36fc2cf0775)