Off the top of my head, this is common when you incorrectly paint foliage outside of the level you are supposed to within world composition…
I usually paint foliage by accessing individual levels, if that’s your case, I suggest the same treatment.
Load the level, Set the viewport to unlit so you can see, and place the foliage.
Once done and saved, load the persistent and the level(s). You should see the foliage pop up and stream appropriately.