Light in Particles with SoftShadow flick scene

I create a particle fire Effect with a light associated to the Lights section, that I use to make a little flicker around the fire.
If I use the light with No Shadows, the effect works well but the 3d model that is present outside the fire (this model is an house) has the external walls brighter, like the light pass through the walls.
If I use Soft or Hard Shadows, I don’t have this bright outside the walls, but the light starts flicker around the scene.
Any ideas to fix the problem?

Could it be this known issue?

I’m not sure that is the same issue, because in my project I use a point light used in the particle effect light section, while, in the known issue is written that the point or spot light don’t create problems.