Repro steps:

1. Open ParticleTests_SubEmitterModule scene from attached project.
2. Press play.
3. Observe:
- how the collision of the color particles appears under the surface of the collider. (gif included)
- how periodically some sub emitters will get spawned to the right (gif included)
4. Exit out of play mode and drag the parent color particle system in the scene view.
5. Observe how at the end of the purple / beginning of the blue particles, a burst of white particles gets spawned.

Expected outcome(s): particles to collide with collider, sub emitters to appear above collider, no random bursts of particles to be spawned

Notes:
- Regression: collision worked in b1, a change was introduced in b2.