The replication agent for the Brand portal cannot publish or unpublish the images from AEM to the brand portal.
On click of test connection, it is showing an "OK" message, whereas while doing the actual publish it fails with "400 Bad requests" response from the Brand portal.
I can see this message at the end of the replication log -
error: com.day.cg.replication. ReplicationException: Repository error during node import: Access denied.
also sometimes this error
Using OAuth 2.0 Authorization Grants
Reference to access token provider is using deprecated accessToken Provider Pid, use accessToken ProviderName instead. Value is com.adobe.granite.auth.oauth.accesstoken.provider. 129b2d9b-53c8
Sending POST request to https://xyz.brand-portal.adobe.com/bin/receive?sling: authRequestLogin=1
OAuth 2.0 User: brandportal-imsconfig-service
OAuth 2.0 User: brandportal-imsconfig-service sent.
Response: 400 Bad Request