Try adding this script to the emitter and adjusting the Render Order past 3000. Also make sure the depth of the Ortho Camera is deep enough and you clipping planes are big enough.
public class RenderQueue : MonoBehaviour
{
public int renderOrder = 0;
int lastRenderOrder = 0;
void Start()
{
renderer.material.renderQueue = renderOrder;
lastRenderOrder = renderOrder;
}
void Update()
{
if (renderOrder != lastRenderOrder)
{
renderer.material.renderQueue = renderOrder;
lastRenderOrder = renderOrder;
}
}
}