Vertex painting not working at all in ue 4 and 5

Hi there, i’ve been trying to get vertex painting to work on ue all week, and the only way it kind of works is using a height lerp, but even then it doesn’t blend well and it doesn’t take into account the height map, so im unable to get a realistic look.
i cant use any other nodes, as the materials dont show up. Now, as you can see from the image i can paint, but the materials just don’t work.
i would be eternally grateful if someone can help ahahah