Hi, I created a trigger to populate a field on the Work Order Object.

SVMXC__SVMX_Event__c  = ServiceMax Event Object
SVMXC__Service_Order__c = Work Order Object

My trigger:

trigger secondTechnicianValidation on SVMXC__SVMX_Event__c (after update, after insert) {
    
    //store the Work Order id
    Set<ID> wo = new Set<ID>();
    
    for(SVMXC__SVMX_Event__c svmxEv : Trigger.New)
    {
        wo.add(svmxEv.SVMXC__Service_Order__c);

    }
    
    System.debug('woOrderId is: '+ wo);
    
    
    //-----------------Store the ServiceMaxEvents related to the current Work Order--------------------------------------//
    List<SVMXC__SVMX_Event__c> allEventsForAWo = [Select SVMXC__Service_Order__c, SVMXC__Technician__r.SVMXC__Salesforce_User__r.Email from SVMXC__SVMX_Event__c where SVMXC__Service_Order__c =: wo];
    System.debug('ServiceMax Events related to this Work Order are:  '+ allEventsForAWo );
    
    
    //----------------Store the emails of Technicians from these ServiceMax Events --------------------------------------//
    Set<String> emailTechniciansServiceEvents = new Set<String>();
    for(SVMXC__SVMX_Event__c smvxEvent : allEventsForAWo)
    {
         emailTechniciansServiceEvents.add(smvxEvent.SVMXC__Technician__r.SVMXC__Salesforce_User__r.Email);
    }
    System.debug('Emails of the technicians are: '+ emailTechniciansServiceEvents );
    
    // ---------------store the Work Order object which it needs to be updated with the emails of the technicians --------//
    List<SVMXC__Service_Order__c> storeWorkOrders  = new List<SVMXC__Service_Order__c>();
    for(Id woId : wo)
    {
        SVMXC__Service_Order__c order = new SVMXC__Service_Order__c();
        order.id = woId;
        storeWorkOrders.add(order);
    }
    System.debug('storeWorkOrders' + storeWorkOrders);
    
    //-------------------loop through each work order -----------------------------------------------//
    List<SVMXC__Service_Order__c> woToUpdate= new List<SVMXC__Service_Order__c>();
    for(SVMXC__Service_Order__c wos : storeWorkOrders){
         wos.TechniciansEmail__c = String.join(new List<String>(emailTechniciansServiceEvents), ', ');
         woToUpdate.add(wos);
    }
    System.debug('woToUpdate' + woToUpdate);
    
    //-------------------update the list-----------------------//
    if(!woToUpdate.IsEmpty()){
        update woToUpdate;
    }
}

Everything works fine with a single record when I edit the Service Max event... but... when I use data loader to mass update it doesnt work correctly.

This is my debug with a single record:

Everything is fine as you can see.. Any idea why with data loader is not working correctly?