Hi, I have a trigger that updates a field on a custom object, Pitch.  I got it to partially work with help from ChatGPT and my own tweaks.

1. What it does is update a field that shows the total of all Opportunity Amounts related to a specific Opportunity Property Group.
2. Next it should find all other Pitch records that have the same Opportunity Property Group do the same update so all related records should be in sync.

ie Select SUM(Opportunity__r.Amount) From Pitch__c where Property_Group__c = :record.Property_Group__c

It does not do step 2 but I can't figure out why.  Any idea?

trigger calculatePropertyGroupAmountBeforeFull on Pitch__c (before insert, before update) {
  // Get the records that are being triggered on.
  List<Pitch__c> records = Trigger.new;

  // Get the property group amount for each record.
  for (Pitch__c record : records) {
    List<AggregateResult> propertyGroupAmounts = [

      SELECT SUM(Opportunity__r.Amount)
      FROM Pitch__c
      WHERE Id = :record.Id OR     
     Property_Group__c = :record.Property_Group__c
      GROUP BY propertyhighspot__r.Property_Group_Text__c

    ];

    // Set the property group amount for each record.
    if (propertyGroupAmounts != null && propertyGroupAmounts.size() > 0) {
      record.Property_Group_Amount__c = (Decimal)propertyGroupAmounts[0].get('expr0');
    } else {
      // Set the property group amount to 0 if there is no amount.
      record.Property_Group_Amount__c = 0;
    }
  }

  // Check if the trigger is currently running.
  if (RecursiveTriggerHandler.isFirstTime) {
    return;
  }


  // Get the property group amount for each record.
  for (Pitch__c record : records) {
    List<AggregateResult> propertyGroupAmounts = [
      SELECT SUM(Opportunity__r.Amount)
      FROM Pitch__c
      WHERE Id = :record.Id OR Property_Group__c = :record.Property_Group__c
      GROUP BY propertyhighspot__r.Property_Group_Text__c
    ];

    // Set the property group amount for each record.
    if (propertyGroupAmounts != null && propertyGroupAmounts.size() > 0) {
      record.Property_Group_Amount__c = (Decimal)propertyGroupAmounts[0].get('expr0');
    } else {
      // Set the property group amount to 0 if there is no amount.
      record.Property_Group_Amount__c = 0;
    }
  }

  // Update all records with the same value for Property_Group__c.
  List<Pitch__c> matchingRecordsToUpdate = new List<Pitch__c>();
  for (Pitch__c record : records) {
    if (record.Property_Group__c != null) {
      // Get all records with the same value for Property_Group__c.
      List<Pitch__c> matchingRecords = [
        SELECT Id, Property_Group_Amount__c
        FROM Pitch__c
        WHERE Property_Group__c = :record.Property_Group__c
        AND Id != :record.Id
      ];

      // Update the property group amount for all matching records.
      for (Pitch__c matchingRecord : matchingRecords) {
        if (!matchingRecord.IsUpdated__c) {
          matchingRecord.Property_Group_Amount__c = record.Property_Group_Amount__c;
          matchingRecord.IsUpdated__c = true;
          matchingRecordsToUpdate.add(matchingRecord);
        }
      }
    }
  }

  // Update all matching records outside of the trigger context.
  if (!matchingRecordsToUpdate.isEmpty()) {
    update matchingRecordsToUpdate;
  }
}

Apex Class
public class RecursiveTriggerHandler{
public static Boolean isFirstTime = true;
}