Generating Multi Terrain is Freezing with "The Scene is Invalid."

[Topthink]

I'm on my fifth project today, all going poorly.  I'm working on a totally stripped down project, only Unity 2021.3 and Gaia Pro 2021.  I'm trying to create a 10x10 terrain (256^2) and I seem to be having difficulty.  I'm getting a "....The scene is invalid...." message after creating twenty or so of the 100 sections.  I've had the problem on other size Multi Terrains as well.  

 

[Bryan]

It sounds like you are running out of memory. 
What are you pc specs?