Hello, I had the same problem and just found the work around changing 2 things (for every mesh, lol), I’m using 4.24.3 version of the engine in case you don’t have the same tools or menus.
- A lot of my meshes had too much triangles, for example I had a tiny TV Remote Control over 500.000 triangles. For this issue you can open the **Statistics **Viewer (from main toolbar Window->Statistics), select Primitive Stats from the first dropdown menu and order your meshes by Tris, if you see something like my Tv RC mesh problem, open the Static Mesh Editor for every mesh and in details panel under LOD 0->Reduction Settings low the Percent Triangles for the mesh. I have a mesh statistics inside the editor viewer to see the quantity of triangles and you actually see the effect of lower percentage have in your mesh for desired results.
- The other thing to change is the lighmap resolution of your meshes. You can see the lightmaps for all your objects in scene by clicking the lightning dropdown menu inside the main editor (for me LIT->Optimization Viewmodes->Lightmap Density), where green is low resolution and red is high resolution, try green and see if this was causing the error, you have to read more about this to know whats the best configuration for your project. In details panel of every mesh under **Lightning **check the Overridden Light Map Resolution and play with it to find the result you want. Or you can change the lightmap for all of your objects clicking the small arrow to the side of Build button->Lightning Info->Lightmap Density Rendering Options, play with the Ideal and/or **Maximum **to get the result you are looking for.
You can make the number 1 tip on your 3D tool of your preference too, I guess its more recommended.
Hope it can help other people with the same problem, have a blessed day.