Yes, I see what you mean, they do come empty and unusable now.
The user has to do more steps now to get it working, which it should be by default.
As a workaround, I tested the default, standard and customizable landscape types and if you use the Auto-Fill Target Layer Assets button, put a check in the Create new assets in the default folder if none are found box then click on All Layers it looks like it functions as normal and you can paint the layers.
Oh wow, I’ve been stagnating on the same landscape materials for so long, these other ones look cool
Edit: I just considered the workaround advised above may clear existing paint detailing and should only be done for new landscapes