Steps to reproduce:
1) open attached project
2) play scene 'TestScene'
- the scene has three cubes, bottom right corner shows expected behavior and upper left shows bug
3) press key 'X' (adds TargetJoint2D)

Expected behavior: collides with the cube in middle
Actual: ignores collision

Workaround: collision starts working if the inspector values of the TargetJoint2D are changed

Reproduced: 5.3.0f4, 5.3.1p4, 5.4.0b3