I have a before insert and update trigger that updates two writeable fields in the account based on custom setting fields. When I test manually, the trigger works. However, my test code is failing. The account name is saving but the trigger to update continent and region doesn't seem to run. I added start test and stop test around inserting the accounts but that doesn't seem to help. How do I ensure the trigger runs and updates the account a3? 

@isTest
private class Test_AccountTrigger {

    static testMethod void test() {


       //create 2 accounts -  billing country not in list, billing country in list
        Account a2 = new Account();
        a2.Name = 'invalid country';
        a2.billingcountry='alsdkfjasd;if';
        a2.industry = 'Agency';
        a2.Annual_company_revenue__c = 'under $100M';

        Account a3 = new Account();
        a3.Name = 'valid country';
        a3.billingcountry='Germany';
        a3.industry = 'Agency';        
        a3.Annual_company_revenue__c = 'under $100M';

        
        Test.startTest();  
                insert a2;    
                insert a3;
        Test.stopTest();
                  
                
        // Query the newly inserted records
        Account aa2 = [Select Name, Continent__c, Region1__c FROM Account where Id = :a2.Id];
        Account aa3 = [Select Name, Continent__c, Region1__c FROM Account where Id = :a3.Id];
        System.debug('aa2 ' + aa2.Name + ' continent = ' + aa2.Continent__c);
        System.debug('aa3 ' + aa3.Name + ' continent = ' + aa3.Continent__c);

        // If the trigger works, then territory and region will only be set on last account
        System.assertEquals(null, aa2.Continent__c);
        System.assertEquals(null, aa2.Region1__c);
        System.assertEquals('Europe',aa3.Continent__c);
        System.assertEquals('EMEA', aa3.Region1__c);
       

    }
}