3793894 - Error AADSTS50105 when using EntraID as IdP and IAS as proxy

• Sign-in to the application via the corporate identity provider configured and Identity Authentication Service (IAS) as proxy.
• Sign-in via the default identity provider works.
• Error message: "AADSTS50105 - The signed in user isn't assigned to a role for the application."

Identity Authentication Service

identity authentication service, ias, azure ad, microsoft entra id, aadsts50105, user not assigned to role, enterprise application, custom identity provider, conditional authentication, sso failure, login error, access denied, role assignment, application assignment , KBA , BC-IAM-IDS , Identity Authentication Service , Problem