To reproduce:
1. Open project Test
2. Open testScene
3. Notice the four cubes and spheres in the scene. The spheres create the explosions. Three of the object pairs are identical copies, while the fourth pair has been copied and then rotated slightly.
4. Enter play mode and notice how the fourth cube gets thrown into the air even though the sphere is not inside/below the cube.

Note: if you were to rotate the fourth pair back into a similar position like the other pairs, everything would work fine.