Using the 8-direction movement with solid objects seems to bug it out a bit if the walls are too thin (at least 16px).
Steps to reproduce:
1. Add 8direction and solid behaviors to 2 objects
2. Add a tilemap (so you can have walls, but any solid will do) that has 16x16 tiles
3. Add controls to both objects
4. Hug any wall with both characters and make one of them block the other from behind
5. Either hold the same direction for both objects, or if nothing happens, try to move backwards with the object that's hugging the wall.
Use WSAD to move one player next to a wall. Use the arrow keys to stand behind that player. Release everything and use WSAD again to try and move backwards, into the other player that's blocking you.
If you were hugging a wall on your left or above, the player that's closest to the all warps all the way around it.
If you were hugging a wall to your right or bottom, the players can't even hug it - they'll start warping between it each other.
Here's a gif showing it:
And here's a capx:
Note that this does not happen if the objects and the walls are at least 32px by 32px.