Hi, I utilized ChatGPT to help create a trigger.  It seems run but does not seem update.  From using the debug log it says "21:29:14.0 (164719242)|VARIABLE_ASSIGNMENT|[5]|pitch|null|"  Can I get assistance understanding why it passes as null?

I essentially want:
1. If a value is set on CustomObject__c for CustomFieldId__c, which is a lookup to Product2, I want Salesforce to find the value for CustomFieldId__r.Property_Group_Text__c.
2. Then I want Salesforce to search all Records from CustomObject__c who have the same CustomFieldId__r.Property_Group_Text__c value
3. And find the SUM of Opportunity_Amount__c, which is populated when the Opportunity is added.

I have tried updating Property_Group_Text__c on the CustomObject and then running second trigger but I'd have problems with the record being in read only mode, so I figured I'd try to have this trigger do two things do the lookup as well.

If I could find some way to have the field on the CustomObject show the Sum of the Opportunity Amounts, either by lookup or by a field on CustomObject as shown, I'd be very appreciative. Aron

trigger UpdateTrigger on CustomObject__c (after insert, after update) {
    Set<String> updatedPropertyGroups = new Set<String>();

    // Loop through the trigger records and add their updated Property_Group_Text__c values to the set
    for (CustomObject__c CustomObject : Trigger.new) {
        if (CustomObject.CustomFieldId__c != null && (Trigger.isInsert || CustomObject.Property_Group_Text__c != Trigger.oldMap.get(CustomObject.Id).Property_Group_Text__c)) {
            updatedPropertyGroups.add(CustomObject.CustomFieldId__r.Property_Group_Text__c);
        }
    }

    // Query the Opportunities related to the updated CustomObject records and Property_Group_Text__c
    List<AggregateResult> results = [SELECT SUM(Opportunity_Amount__c) sumAmount, Property_Group_text__c propertyGroupValue                                      
    FROM                                       
    WHERE CustomFieldId__c IN :Trigger.newMap.keySet() AND Property_Group_text__c IN :updatedPropertyGroups                                     
    GROUP BY Property_Group_text__c];

    // Create a map of Property Group Text values to their SUM(Opportunity__r.Amount) totals
    Map<String, Decimal> propertyGroupAmounts = new Map<String, Decimal>();
    for (AggregateResult result : results) {
        propertyGroupAmounts.put((String) result.get('propertyGroupValue'), (Decimal) result.get('sumAmount'));
    }

    // Create a list of CustomObject__c records to update
    List<CustomObject__c> CustomObjectesToUpdate = new List<CustomObject__c>();

    // Loop through the updated CustomObject records again and update their Property_Group_Amount__c field
    for (CustomObject__c CustomObject : Trigger.new) {
        if (updatedPropertyGroups.contains(CustomObject.Property_Group_text__c)) {
            CustomObject.Property_Group_Amount__c = propertyGroupAmounts.get(CustomObject.Property_Group_text__c);
            CustomObjectesToUpdate.add(CustomObject);
        }
    }

    // Perform a DML update on the list of CustomObject__c records
    if (!CustomObjectesToUpdate.isEmpty()) {
        update CustomObjectesToUpdate;
    }
}