Ue4 shadow problem on the cube

I’ve been trying to solve this problem for about two days,
no settings of the project have been changed from its default setting. Mesh’s lightmap resouliton is fine. but I still encounter such a problem when I put objects such as walls and floors side by side. I tried almost everything but couldn’t solve the problem. What is the solution to this?

Ok, do you have a importance volume around the lot and try ( lightmass settings ) setting indirect lighting scale to 0.1-0.15 and 0.6 for smoothness.

I tried it, it is not worked much, but setting static lighting scale to a lower value works. But it has some disadvantages. Like a lot longer build times. So I decided to use a one mesh, for all walls. That mean I created the walls via another program. But yeah this problem doesnt occur for it. It’s fine now