Hrm... this isn't working for me. The first planet generates trees, and ones with the full Alien Biomes array work sometimes, but Nauvis-alikes never do after the first one.

Any ideas?

Have you made sure to save after running the command? It works fine for me and a friend playing multiplayer. I haven't tried this with SE or warptorio expanded though

I am using Warptorio Expanded, but I think the issue was a combination of the tree bug in Warptorio plus an odd combination of circumstances.

See... before this I was playing Nullius. Apparently, it had set all vegetation to "Disabled" in Alien Biomes' settings, and that carried over to this. So Nauvis-likes weren't getting trees because of the bug, and then alien worlds weren't getting trees because it was being told not to generate them. xD

Not something you need to fix, of course.

Gotcha. Glad you figured it out