How to use store world trees in CAW?

I have sunlit tides installed and want to use its trees in my new world. I can only place them by going into EIG then World Editor. They look beautiful but then they disappear when I go back to CAW. I thought maybe they were there but invisible but they are also not there when I export. I was able to use store trees in previous worlds. I want the in the landscape, not on lots. Thanks if anyone can advise how to make this work.