Not sure if this is a solution for your problem, but here are some steps to get you in the right direction:
-
On the Niagara system placed in your level (or spawn from Sequencer), enable “Render CustomDepth Pass” (same as for any other mesh you want in the custom depth
-
On the materials used for your effect, enable “Allow Custom Depth Writes”. This will make your sprites show up in the custom depth pass. Thou the sprites wont get a semi translucent mask, but maybe that is better than nothing?
