Where the RP is trusted in SSO and configured to auto-authorise, and the user has previously authorised SReg attributes, the AX attribute form is never presented to the user, so the AX attributes don't get passed back to the RP.
Where the RP is trusted in SSO and configured to auto-authorise, and the user has previously authorised SReg attributes, the AX attribute form is never presented to the user, so the AX attributes don't get passed back to the RP.