Vertex Color Information Lost on Editor Restart

This is a regression. In 4.19 and Main (CL 4008322), vertex color information does not save properly and data is lost when editor is reopened. Creating project from scratch instead of copying over from 4.18 results in crash ([Link Removed])

Per licensee:

We recently updated our project from 4.18.3 to a custom built 4.19.1 and having now problems with the vertex color on our skeletal mesh cars.

We are using a grey vertex color as an inital value for our cars but somehow their vertex color ends up plain white after the editor restart.

When I'm repainting the grey vertex color and save the skeletal mesh. I end up with the same white vertex color when I shut down the editor and reopen it...

Apparently the problem is that Vertex Color data of Skeletal Meshes is not saved when clicking the Save button in the Paint Tool.

I've discovered a possible workaround: After painting a Skeletal Mesh, open that same Skeletal Mesh from the Content Browser, change the "Allow CPUAccess" Property of "LOD 0" and save. (Might work with other properties as well.) Then change it back and save again.

 

1. Open new empty project in 4.18
2. Copy SkeletalCube (skeletal mesh) from Engine to Content folder
3. Drag SkeletalCube from Content Browser into level.
4. In Modes tab, select Paint > Colors tool
5. Change Color View Mode to RGB Channels
6. Paint SkeletalCube a bright red color.
7. Save all, Close project, reopen.
8. Drag SkeletalCube from Content Browser into level.
9. In Modes tab, select Paint > Colors tool
10. Change Color View Mode to RGB Channels
    • Notice it looks the same as when it was saved. 
11. Open a copy of the project in 4.19
12. Drag SkeletalCube from Content Browser into level.
13. In Modes tab, select Paint > Colors tool
14. Change Color View Mode to RGB Channels

Result: Vertices have lost some color data, so mesh needs to be repainted. Subsequently resaving the project and reopening in 4.19 does not keep color data; vertices always need to be repainted. See attached screen shots.