Solution definition field is "read-only" for admin in Search Resource table utilized for Agent Assist, hence you cannot use custom Similarity solutions created in the Similarity Framework within Agent Workspace.SummarySteps to Reproduce: Log in to the 'New York' or later instance as an 'admin'2. Open 'Agent Workspace Home' from the filter navigator3. In the 'Lists', open 'Incidents' 4. Details form will be opened for this incident. In the Agent Assistant in the form, we can see the search resources which are associated with the Similarity Framework solutions provided by the applications such as "Predictive Intelligence for Incident Management" ('Similar Incidents, 'Similar Open Incidents' ...)5. Open Search Resources from filter navigator (Contextual Search -> Additional Resources)6. Open the record from the list which name is 'Similar Incidents'7. In the Search Resource form, you can not edit and change the Solution Definition for this search. The searches are associated with OOB Solution Definitions. You would like to associate the searches with your own customized solution definition Reason: The reason is admin can modify the existing solution definition with less changes which are executable but not point to another one, it is a known limitation that due to Contextual Search and Agent Assist required behavior only ServiceNow can modify search sources or search actions, there are no plans to change such configuration.