Ah, yes, this would be the fault of Cotton.
I think I'm right in saying there's no way to get the vanilla trading ships to trade in modded resources except by overwriting their Core definition, which is what I did with cotton. Trouble is that if more than one mod you're using does this, only the changes from the mod that's loaded last will take effect.
I can and will fix this in the next version by creating a separate trader dealing in cotton, but the drawback is that the more types of trader you have, the less chance there will be of a specific one appearing, turning it into a bit of a lottery. Personally that's not to my taste - but nothing to be done about it for now
I think I'm right in saying there's no way to get the vanilla trading ships to trade in modded resources except by overwriting their Core definition, which is what I did with cotton. Trouble is that if more than one mod you're using does this, only the changes from the mod that's loaded last will take effect.
I can and will fix this in the next version by creating a separate trader dealing in cotton, but the drawback is that the more types of trader you have, the less chance there will be of a specific one appearing, turning it into a bit of a lottery. Personally that's not to my taste - but nothing to be done about it for now