Is it after you open it in excel by any chance? That is a known excel issue as it uses general formatting and thinks it is a number, txt file opened in text editor should preserve the 0.
NO. i think this is it, but i just open in cucm (Bulk Administration-Job Sheduler-job id), and i see that this is not exel. CUCM itself gives numbers without "0" in front.
Try downloading the file from 'Bulk Administration/Upload\Download Files' rather than browsing through the job results.