This was posted on the Procedural Parts thread. I have the same issue. However there is a detail. It works fine when you first add a procedural tank/srb to the rocket, the mass is displayed correctly on the VAB and MJ. However when you load a rocket, the dry mass changes to the default(1 for tanks, 3,7 for SRBs). It happens with the other tanks affected by RF as well. Is it just a problem on my end? Can someone confirm please. Basicaly the masses are different when you load a rocket, compared to when you first build it, and MJ is calculating the masses correctly, but the VAB isn't.