This batch job runs once a day every day at 1am.

It works fine 50% of the time and doesn't process or fails the other 50%.  When it fails, I see no error message on the job history at all.  It just fails.

I put on debug logs last week on it and when it failde I noticed it had a very, very long duration (in ms) to process.  So I'm thinking something is causing this thing to time out when it runs, sometimes.

Does anyone see anything wrong with the code and in particular the soql query that might cause a timeout/job failure?  

global class updateAssetTermDates implements Database.Batchable<sObject>, Schedulable{

    string query;
    
    global void execute(SchedulableContext SC) 
    {
        updateAssetTermDates  x = new updateAssetTermDates(); 
        database.executebatch(x);
    }

    global Database.querylocator start(Database.BatchableContext BC){
        Query = 'Select id, Entitlement__r.EndDate, Previous_Annual_Maintenance__c, Annual_Maintenance__c, Future_Annual_Maintenance__c, Term_Begin_Date__c, Term_End_Date__c, Term_Start_Date_Hidden__c, Term_End_Date_Hidden__c  FROM Customer_Asset__c WHERE Term_Start_Date_Hidden__c = TODAY AND Maintenance_Status__c = \'On Subscription\' ';
        return Database.getQueryLocator(query);
    }

    global void execute(Database.BatchableContext BC, List<Customer_Asset__c> scope1){
        List<Customer_Asset__c> assList = new List<Customer_Asset__c>();
        Set<Id> assEntId = new Set<Id>();
        Date d;
        
            for(Customer_Asset__c ca : Scope1){
                ca.Term_Begin_Date__c = ca.Term_Start_Date_Hidden__c;
                ca.Term_End_Date__c = ca.Term_End_Date_Hidden__c;
                d= ca.Term_End_Date__c;
                if(ca.Future_Annual_Maintenance__c != NULL)
                {
                    ca.Previous_Annual_Maintenance__c = ca.Annual_Maintenance__c;
                    ca.Annual_Maintenance__c = ca.Future_Annual_Maintenance__c;
                    ca.Future_Annual_Maintenance__c = NULL;
                }
                
                assList.add(ca);
                assEntId.add(ca.Entitlement__c);
            } 
                  
        try{
                update assList;
        } catch (Exception e) {         
            Error_Log__c log = new Error_Log__c();
            log.trace__c = 'Type: ' + e.getTypeName() + '\n' + 'Cause: ' + e.getCause() + '\n' + 'Message: ' 
            + e.getMessage() + '\n' + 'Line #: ' + e.getLineNumber() + '\n' + e.getStackTraceString() + '\n';
           // + 'Some Custom Variable Information From Class: ' + myClassVariable;
            insert log;         
        }        

        List<Entitlement> entList = new List<Entitlement>();
        
        for(Entitlement e: [select id from Entitlement where ID =: assEntId]){
            e.EndDate = d;
            entList.add(e);
        }
        
        try{
                update entList;
        } catch (Exception e) {         
            Error_Log__c log = new Error_Log__c();
            log.trace__c = 'Type: ' + e.getTypeName() + '\n' + 'Cause: ' + e.getCause() + '\n' + 'Message: ' 
            + e.getMessage() + '\n' + 'Line #: ' + e.getLineNumber() + '\n' + e.getStackTraceString() + '\n';
           // + 'Some Custom Variable Information From Class: ' + myClassVariable;
            insert log;         
        }
        
    }

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