I'm on Craft 188.8.131.52
My multisite setup is using different domains.
If I'm on a.com, I can Live Preview everything on b.com fine, except the homepage.
I get the error
Access to XMLHttpRequest at 'b.com' from origin 'a.com' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.
If I add
Access-Control-Allow-Origin * to my Nginx config, none of the pages work and it complains about a duplicate value of (a.com, *).
Any ideas? Other questions I've browsed all suggest this has been fixed in Craft 3.1, and none of the docs indicate the I need to do anything to get this to work.