I have a batch apex job that basically goes through all invoices and totals the amounts for each sales person for each month and year.  The job works as expected in the sandbox environment with the test data I created.  But when I moved the job to production, it runs without errors, but does not update the fields with the monthly invoice sum totals like it does in sandbox.  In reviewing the logs I found one for example that found totals and shows that it updated the fields for the months.  Then in the very next log that did not find any invoices with totals, it updated the fields with null values for the very same records as in the prior log.  The Forecast and Forecast detail objects were created from scratch for this batch job and have no other triggers or processes running against them to udpate any fields.  My code is below, can anyone see why it is not updating the sum fields properly?

global with sharing class Forecast_Batch implements Database.Batchable<sObject>, Database.Stateful{

        global Database.QueryLocator start(Database.BatchableContext BC)
        {
            return Database.getQueryLocator([SELECT Id,OwnerId FROM Account]); //Query all accounts for ID and OwnerId
        }

    global void execute(Database.BatchableContext BC, List<SObject> scope)
    {        
        Map<Id, Map<String,Decimal>> accountAmountMap = new Map<Id,Map<String,Decimal>>();

        List<Id> accountOwnerIds = new List<Id>();
        Set<Id> accountIds = new Set<Id>();
        
        system.debug('+++ SCOPE SIZE ' + scope.size());
        
        for (SObject s : scope) {
            
            Account acc = (Account)s;
            if(!accountIds.contains(acc.Id)){
                accountIds.add(acc.Id);
            }
            
        }
        
        for (Account acc : [SELECT OwnerId,(SELECT Amount__c,InvoiceDate__c,OwnerDetails__c,Inv_Yr__c FROM Invoice__r ) FROM Account WHERE Id in : accountIds]) {
            
            Map<String, Decimal> amountMap = new Map<String, Decimal>();
            
            for (Invoice__c inv : acc.Invoice__r) {
                 
                Decimal amount = amountMap.get(inv.OwnerDetails__c);
                if (amount != null) {
                    amountMap.put(inv.OwnerDetails__c, inv.Amount__c + amount); 
                } else {
                    amountMap.put(inv.OwnerDetails__c, inv.Amount__c); 
                }
            }
            accountAmountMap.put(acc.Id, amountMap);
            accountOwnerIds.add(acc.OwnerID);
            
        }
        System.debug(accountOwnerIds);

         // Query list of forecast details record based on Account's owner Id

        List<Forecast_Details__c> forecastdetails = [SELECT ID,Name,Month_Total__c,OwnerID__c,FDOwnerDets__c from Forecast_Details__c where OwnerID__c IN : accountOwnerIds];

        // Iterate accounts in for loop
        // iterate forecast details record
        // get invoice amount based on account id and forcast month.
        // update in forecast detail record.

        for (SObject s : scope) {
            Account acc = (Account)s;
            Map<String, Decimal> amountMap = accountAmountMap.get(acc.Id);
            for (Forecast_Details__c forecastDet : forecastdetails) {
                if (forecastDet.OwnerID__c == acc.OwnerId)
                    
                {
                    Decimal amount  = amountMap.get(forecastDet.FDOwnerDets__c);  
                    forecastDet.Month_Total__c = amount;
                    System.debug('match');
                    System.debug(amount);
                }
            }
        }
        System.debug(forecastdetails);
        update forecastdetails;
    }  

    global void finish(Database.BatchableContext BC){}
} 


I really appreciate any assistance that anyone can provide!