[SOLVED] Particle Systems with the same material not being batched

I've noticed that Particle Systems that share the same material are not batched on the device, but they seem to be batched in the editor. I have dynamic batching on. Is this intended, or is it a bug? Or maybe I'm doing something wrong...

Unity 2018.3.0f2
tested on iPhone 7 using XCode + GPU frame debugger

 

if it's a rendering issue, why do they get batched in the editor, but not on the device?

I've tried various things but still failed to make it work
this is my case:

I have 1 prefab with 2 different particle systems (different materials as well) [layer X]
- glow fx is closer to the camera
- shadow cookie fx is in the back (lower render queue in the shader as well)

6 instances of that prefab are created at the beginning and then rendered into a small render texture (with no depth) by a camera that only renders layer X

expected result: 2 draw calls
the actual result: 12 draw calls

 

hey Richard, Karl gave me the same link previously, but I somehow managed to miss this line

Now it makes more sense.
I was not expecting you guys to be so responsive, especially these days so thank you!