I don't know why it is like this, but I have tried factory resetting mechjeb-dev but it did not fix it. As I already mentioned I got all the mods from the RP-1 express install, I also recently removed the headlines mod and I was wondering if that might be the problem that is causing this delta-v bug for me? Edit: I'm stupid, the fact that the decoupler node was so close to the other node made me realize what the problem was