Q Business - Identity Provider and Zendesk data source user mapping

I created a new user in IdP (IAM Identity Center) and subscribed them to my Amazon Q business app. The app has a connector to Zendesk, which indexed the data. The user with the same email as a new one in IdP does not exist in Zendesk.
Due to an enforced ACL on the Application side, this user is now not getting any Zendesk-relevant results in chats.

So I did a user update: aws qbusiness update-user --application-id ... --user-id iamuser@email.com --user-aliases-to-update '[{ "indexId": "...", "dataSourceId": "...", "userId": "-1" }]' I set userId to -1 which is a random identifier that came to mind. Does it have any relation to the Zendesk user, or does it not matter?

I have assigned a user to a group aws qbusiness put-group --application-id ... --index-id ... --group-name "NAME OF MY ZENDESK USER GROUP" --data-source-id ... --type DATASOURCE --group-members '{ "memberUsers": [ { "userId": "-1", "type": "DATASOURCE" }]}'

Bu i'm still not getting any relevant results in the chats from the indexed Zendesk. Is there something I'm overlooking?