Basically, after painting the vertices, I noticed that at some point while editing my scene, they disappeared ... and I tested every step i did before to find out what was causing it to disappear. I found that, for some reason, entering edit mode and exiting edit mode deleted my vertex painting. So I recorded a video showing exactly how it happens:
My thought about it: For some reason the vertex paint goes 100% white, that is the default color when you create a new one. I know it could happen if u decimate or somehow change the amount of vertex of your object, but I'm just entering edit mode and not changing anything... I don't know if its a bug or I am doing something wrong. pls help!