Evening all, i am hoping for your help.

I have created this batchable class and tested it in sandbox, all working in sandbox, 100% code coverage. But it fails to run in production.

Preparing timesout. I can't see why as the full sandbox has just as much data as production. I have checked access rights to all necessary fields.

Help please. :-(
 

global class ProspectScoreLeadTask implements Database.Batchable<sObject> {
    
    global integer recordsProcessed = 0;
    
    global Database.QueryLocator start(Database.BatchableContext bc){
        return Database.getQueryLocator([SELECT Id, WhoId, ScoreTask__c FROM Task WHERE WhatId = null AND IsLead__c = true AND CreatedDate = LAST_N_DAYS:365 ORDER BY WhoId ASC, ScoreTask__c ASC]);
        
    }
    
    
    global void execute(Database.BatchableContext bc, List<Task> scope){
        
        Map<Id,Lead> leadMap = new Map<Id,Lead>();
        for(Task tsk : scope){
            leadMap.put(tsk.WhoId,new Lead(Id = tsk.WhoId, ScoreTask__c = tsk.ScoreTask__c));
            recordsProcessed = recordsProcessed + 1;
        }
        Lead[] leadUpdates = new Lead[]{};
            for(Id id : leadMap.keySet()){
                leadUpdates.add(new Lead(Id = id, ScoreTask__c = leadMap.get(id).ScoreTask__c, LastScoreRefresh__c = date.today().addDays(2)));
            }
        update leadUpdates;
        
        
    }
       
    global void finish(Database.BatchableContext bc){
        system.debug(recordsProcessed + ' records processed!');
        //AsyncApexJob job = [SELECT Id, Status, NumberOfErrors, JobItemsProcessed, TotalJobItems, CreatedBy.Email FROM AsyncApexJob WHERE Id =: getJobId()];
    }
}