I am using a custom domain for my auth server which is not the same as my apps domain ( auth.somedomain.com).
Logging into both of the apps works fine in a browser tab.
However, when I embed App B into App A, I get an 403 error when trying to execute the sign in flow.
I have enabled the Iframe Embedding option.
Are there any ideas on how I can achieve a seamless sign on experience?