weird reflection, need help!

Hi guys, I am a beginner on UE4, I followed the tutorial which builds an office room with directional light and atmospheric fog, but the reflection is pretty weird like in the picture.
You see, the directional light comes from the top left, and the wall in the left cast a shadow on the marble ground. The weird thing is, the sun and cloud(atmospheric fog) shouldn’t appear on the ground for it should be blocked by the wall, so how to solve this problem?
I am new to UE4 so great thanks for guys paying attention and spending your time replying me!!

After building, the reflection problem is still there…

Place a reflection capture actor inside the room.

Hi Jacky, at first I have reflection capture actor, but it looks not right, it seems the reflection angle is really not realistic. After I removed it, I see there must be a problem. Later this day I will post screenshot with the reflection capture.