All kinds of movable lights should work properly now. Please report any issues you find with the new version.
We found one common source of lighting instability, it’s insufficient shadow depth bias - like shadow acne in voxel space. To help users diagnose issues like that, we added “r.VXGI.EmittanceShadowEnable” cvar: if you set it to 0 and everything becomes stable, shadow maps are to blame. You can tune the depth bias with “r.Shadow.PointLightDepthBias” and similar cvars.
If I understand your question about the unlit shadows correctly, then there should have been some directly lit surface that would illuminate those shadows. Now with multi-bounce support, for example light from the floor can illuminate the ceiling, which will in turn illuminate the shadows on the floor (but that will be a very dim light, most likely).