i went to see if i could add it in with easy development tools and its not listed to fill. and not listed in the mod file for fill types
I'm finally able to be at my PC after about a week due to injury. I had to look into game files(as Silage Additive is base-game), the game doesn't register it as a liquid. I've fixed that and it's posted. I also added something to the XL cutter in that pack as well. My FR pack also got updated and posted.
Could be a map issue. Giants don't have "Silage Additive" setup as a Liquid, for whatever reason. There are a few mods out that correct that. Or it can easily be corrected on any map by adding it to the "Liquid" category in the filltypes.xml file so that the game acknowledges Silage Additive as a liquid.