Man, same thing happened to me, they couldn't find it on the options given they said, so I asked them to show me all the options available on their tablet and I went trough them all, folder by folder, one by one, for like 10 - 15 minutes until we found it, there are a couple electric options you need to enable regarding the towing, they all say something like tow this or towing that... the tech guy was surprised it was even there, he said he never saw it before.
its frustrating we need to do the research in order to make them make it work, but well, it is what it is.