Unauthorized after succesful SAML2 login

Hi,

I'm implementing a SAML2 authentication for a client and so far have set up the following:

• redirect to the IdP login screen
• redirect back to Mendix
• authenticate user and look user up in the DB
• open index-default.html page

Current issue

When the index-default page is opened; I unfortunately see the following message in het browser:

Unable to load https://..url.. /xas/ status: 401", response: Object, status: 401, responseText: "{"result":"Invalid session, please login","autologin_support":false}", xhr: XMLHttpRequest}

Looking into the cache; I notice that a non-persistent SAML2 session exists for an unknown user though no session for the user that seems to have succesfully authenticated.

Question

How can the module say the authentication is succesfull yet it can't create a valid session to return?

Thanks in advance!