Bug in the editor? Any workaround?

I am using 4.21.2. Started with the default FPP level, after some changes to the level switched Allow Static Lighting off. For some reason some actors had no shadows. After some tweaking I have accidentally found that they start making shadows if they are slightly moved. However, it starts z fighting in a place where the walls meet.

  1. Level just opened - no shadow, no z fight.

  1. moved the wall to y=1, shadow appears, z fighting appears. Ctrl-Z will reverse to the previous state (no shadow, no z fighting).

  1. Moving the object back by entering zero again. Shadows left, z fighting left.

Any idea what is going on? Is it a bug?

Any idea, if it is possible to make the shadows appear without having to move manually every object without shadows in the level?

Any idea, if it is possible to make the shadows appear without z fighting appearing as well?

If your meshes are overlapping, you will have Z fighting. Make sure they’re not before building lighting.

Also, if you move things around then you need to rebuild lighting

Yet for some reason there is no z-fighting in the original scene (which is not something I created BTW, it is a scene as provided by the UE folks - do you mean I should be wary of them making such basic mistakes?). Plus, see my answer below:

How do I rebuild lighting if I have switched Static Lighting off and Build lighting in the Build menu is grayed out?

Well, the pictures you provided show the Directional Light and Skylight with the yellow dot, so they are not dynamic, meaning the lights can be built! Maybe the pictures are not representing your current scene anymore?

They do. As I wrote in my inital post, I started with the default FPP scene (and I believe I have not modified lights at all, they are exactly as they were put in the scene by the UE) and later switched Static Lighting off, but I have not touched anything else (yet).

Basically I am trying to switch to dynamic lights, switching Static off was a first, obvious step. And in general it worked, but - as explained in the first post - not for all objects.

Perhaps I need to do more, that’s more or less what I am trying to find out/learn.

If you’re using dynamic lighting you need to change the light types to Movable

The new Learning Portal has excellent courses with different learning paths, and good ones regarding lightning and stuff for visualization. I recommend, I am doing all the courses btw just to extract every knowledge drop possible.

I understand I miss a lot, but it still doesn’t explain why I had to move components to make them make shadows. An object should either make shadow, or not, it shouldn’t depend on changing coordinates back and forth.