Operating system: Win 7 Ultimate 64 SP1
Graphics card: GTX 1060 6GB
Worked: works on 2.79 (just tested it). Haven't had the need on 2.80 prior to couple of days ago ... so don't know if it ever worked.
Short description of error
Only 3 Vertex Color Layers can be seen in the Viewport. You can blind paint more then 3, and it does work when used in the ShaderEditor. But only 3 can be viewed in the viewport. The 4th one is displayed as all black.
So if you have 4 of them and forth one is displayed as black, if you delete one of the other 3 VertexColorLayers - then the forth one is displayed (because now you have only 3 of them again)
Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).
- Creat a Cube
- Add SubdivisionModifier with 5 levels. Apply the Modifier. (This is to create enough vertices for painting)
- Enter VertexPaint and scribble something.
- in ObjectData Tab, under VertexColors add another Layer. Scribble some more
- Repeat previous step one more time ( you will now have 3 layers and everything works fine)
- Repeat previous step one more time. Now you have 4 VertexColor Layers and this is where the bug kicks in. That fourth layer is going to be displayed in viewport as Black.
- If you delete one of the first 3 layers, that fourth one is now displayed in the viewport (because the total of VertexColorLayers is gonna be 3)
If you can not reproduce this. I can provide a startup file with the default cube and 4 VertexColorLayers