SUM license SSO

We have a SUM managing 4 pairs of HA sg650, all are fully licensed but the SUM has suddenly stopped allowing SSO to work. Digging into it all the features seem to be enabled but I'm unable to configure the LDAP etc config. All the items are greyed out and there is a banner stating the license installed doesn't support this.

Can I apply an SG650 license to the SUM or do I need to generate/request a new one from Sophos support.