As discussed in the users list:
When issuing a delegation assertion (Liberty SSOS profile), the following error is logged twice in succession:
ERROR [org.opensaml.storage.impl.client.ClientStorageService:451] -
StorageService shibboleth.ClientSessionStorageService: No storage
object found in session
Presumably the error occurs because the client (presenter) does not support the session cookie, but the client-side storage does not seem useful in the delegation case, and should be skipped.
Attaching an edited trace log (with DEBUG level for opensaml, net.shibboleth.idp.saml.saml2.profile.delegation, and net.shibboleth.idp.saml.nameid).