UE 4.21:: Reimporting Maya mesh causes grey artifacts (patches) over the mesh, why? images attached

Hi, I reimported 1 of my meshes (created with Maya) as usual by simply click reimport, but now, it has big White-grey patches, I haven´t changed anything to that mesh, just updated my Project to UE4.21, i´m not using any texture, it is exactly the same model, it has material aplied with a simple dark color, no normals, no uvs, just color, but the mesh has big squary, horrible patches now, and i canot fix them. why this happened? I´m so scared about UE4.21 reimport
button now. please help!!!

I never had this problem with UE4.20 and 4.19, is this a BUG in UE 4.21?

patchesmesh.png


Here more pics of the mesh after using Unreal 4.21 “reimport” option, this mesh has not any edit, just clicked re-import, btw those grey patches do not cast reflections either, its like if UE did not wanted to apply any material to those areas.

uepatches.jpg

This problem do not happen when i change to “unlit” and its very apparent in “light mode” so it has something to do with light maps, but now that the character is imported, is there a way to fix it in Unreal? and how? i´m new to light maps.

What if you deleted the mesh, and imported it manually without using the reimport button?

Honestly, after reading countless posts of various things many things, that worked in one version of the engine and now it doesn’t after the person upgraded to the lastest and greatest version.

What i have decided to do is this:

Keep the version of the engine that is working installed, and if something stops working in the newer version, I just roll back and keep developing.

I just don’t understand why Epic is doing this?

Take a look on the market place.

Look and see how many products work and then stop working.

It’s enough to ask the question, what is happening.:p:eek:

I found a solution to this problem,

It is actually a light problem, i imported those meshes from maya without UVs in UE 4.18… i did not miss step this, it was not my mistake, i was not creating UVs for some meshes because i was not using textures for them, i simply applied materials with one color for those and obviously i DID used UVs for meshes that had Paint on them for propperly aplying those textures in UE.

The problem is that now that i moved from UE 4.20 to 4.21, reimporting was causing light not to work on meshes without Uvs, because light needs Uvs to render well when you rebuild lights now (auto maps is not auto creating Uvs when a mesh has no Uvs), i never had a reimporting problem before and i have been working this Project since UE 4.18, that´s why i never had to ask about it before.

So i went to my original Maya file, created “auto uvs” for my mesh… since i dont care how uvs are applied for those meshes, exported it replacing the original file, and in UE reimported the file again without problems