Particle emitter problem - particles stay on surface
Hello, I'm just starting with particles and I have a problem (most likely very silly) with particle emitter. I want to add some floating dust or ash into my scene. I have some geometry and one animated camera. That's it. The problem is, when I create flat polygon to emit the particles from its surface (using Particles > Emit form object), the particles appear and stay on the surface and shake a bit when I play the animation, instead of being emitted. It's a clean scene, without any caches, history, with default particle settings, etc.
If I create the polygon with emitter in a separate scene (and it works the way it should) and then I import it into the main scene, the situation repeats - instead of flowing, particles now stay on the surface.
Any advice would be greatly appreciated.