I am trying to run a SOQL query in workbench to pull details related to the Event (standard object) owner. I've been able to user Owner.Name within the query but haven't been able to successfully reference custom fields on the owner's user record. Any suggestions? I feel like I may have run into a polymorphic mess, but want to get other's thoughts as well. I've bolded the part of the query throwing the error.
SELECT Activity_Area__c,Subject,ActivityDate,Owner.Name,Owner.Tier_4__c FROM Event WHERE Activity_Area__c = 'Sales - Mobility' AND (IsArchived = True OR IsArchived = False) AND (ActivityDate = THIS_YEAR OR ActivityDate = LAST_YEAR)