Well... I could in fact repeat the phenomena in the clean scene by adding a Environemt Sun as shown in this video. If anyone want to test you can download both model and project here StrangeShadows.zip
The issue is because of the 90 degrees angle between the wall surface and directional light.
As a quick workaround you can try rotating your light a bit.
I'll remember about this issue to see if I can do something about it on the engine side.
Aha. Okay. No problem when I know how to avoid it. Thanks
Later:
Yes. Confirmed. This can be avoided by rotating the wall around it y-axis.
Preferable more than 15 degrees. In case of a building or even a city block
I would think that this means that the complete block has to be in more than
15 degrees y-angle to the sun
(This post was last modified: 07-14-2015 10:28 AM by rstralberg.)