Steps to reproduce:

1. Open attached project
2. Open scene "repro"
3. Select "GameObject (1)" and notice that it has composite collider 2D
4. While Game Object is still selected run the scene
5. Notice that after it collides with another collider it starts to twitch/bounce until it get settled few seconds later

Additional steps:
6. Stop the scene
7. Uncheck "Used By Composite" checkbox and run scene again
8. Notice that this time collision happens without any problems

Reproduced with: 5.6.0b3