unable to search and invalidate user session within XUI

Bug description

Unable to perform a fuzzy search within the sessions tab  in the XUI admin console:  Realm > testrealm > session > Username:

The behaviour for AM when a Datastore is present is correct. e.g.: 
type: de 
found: demo, dean 
select: demo 
demo's sessions are listed.

The behaviour for users from external* store is not the same. For example: 
type: de 
found: nothing 

How to reproduce the issue

1. AM vanilla install

2. Created a new realm called testrealm 

Realm > New Realm > testrealm 

3. Created a new chain called testchain which contains the LDAP module set to required

Realm > testrealm > Authentication > Chains > Add Chain > Name = testchain > Create > Add module > LDAP : Required
4. set the testchain as the default authentication for the testrealm

5. I then removed the embedded DS store under the testrealm 

Realm > testrealm >  Identity Store > OpenDJ > remove

6. Then access AM as follows using an incognito tab 

http://openam.example.com:8080/openam/?realm=testrealm 

and login with demo : changeit

7. When i return to access AM as amadmin and view the sessions as follows :

Realm > testrealm > session > Username = de 

Nothing appears, this because the search uses the configured Datastore to search for the usernames. 

Expected behaviour

search the active session based on username fuzzy search. 

Current behaviour

the search field under session currently search the configured Datastores UIDs.