Okay let’s walk down the list.
First, when working in a new UE5.6 project, Niagara opens and functions fine.
Next I deleted the Niagara.ini from the saved/config folder of my project, repoened the project but it still crashed.
I opened it again and tried the “RecompileShaders All” prompt, only took about 15 minuets but when openening any niagara asset it still crashes.