I have reported a case 892393 about assertion failed errors which leads to editor crash in Unity 5.6. As told by the bug report team this is triggered by NOT parenting the particle sub emitter under its "master" emitter and there are more than 1 master emitter linked to the same sub emitter. TBH I won't say I would be surprised at the reason for such change of structure (performance?), but it also means that in Unity 5.6 onward we are required to duplicate the same sub emitter per each master emitter to avoid the assertion failed errors. This can be a problem or even nightmare of organization when we have a bunch of sub emitters linked to multiple master emitters as shown in the project of my bug report. While it may not be relevant to the designer of Shuriken, I never ever parent sub emitter (and I even intentionally break the default parenting of sub emitter) because of a limitation of Unity editor that you can't modify the grandchild or younger descendant of a prefab in project folder, you must drag the prefab to hierarchy, edit and apply it which can be cumbersome when you are playing the scene but want to modify the prefab on the fly.