Bug with Trapcode Particular
This one is not easy to describe.
Let's say you have one layer with Particular effect (layer A). As the particles source, you have selected "Sprite", and the Sprite is a precomp, or any other source that CAN be rasterised (like an Ai file, for instance). But you chose NOT to rasterise it.
Everything works well at that stage. But later in the workflow, you create a second layer (B) with Particular, and decide to use the SAME layer (or precomp) as the source of your particles for layer A.
What happens then is the problem: After Effects chooses to rasterise your source layer, without warning, and even if this layer is locked! As a result, the appearance of your particles changes on ALL layers using this layer as a source for your particles, and good luck with that, if you don't know about the bug. It can stop you in your tracks for hours on end, if you are even lucky enough to notice what happened. It is quasi impossible to guess why the particles on layer A started to go south, especially if you set it up days earlier in the process. Anyone hit that one before?
Hervé Jacquet commented
Thanks for your answer Harry. I had multiple instances of particular in my comp, at different times on the timeline, but using the same kind of particles each time. That is why I had several layers using the same particle source, but a different instance of the effect. Have a nice day.
Harry Frank commented
Definitely sounds like a bug. I will forward to the folks that handle bugs like this at Maxon. And although it does sound like a bug, it is rare that you actually need TWO copies of Particular in one comp as each instance of Particular can contain up to 16 particle systems.