Expense Reports stuck in status and not paying

Hello everyone-

We are having a problem with some of our Expense reports sticking in 'approved' status and not paying.  We have determined that the cause of this is the proj_mgr_flag on the EX_SHEET_HDR record is erroneously set to 'Y'.  When we sql update the proj_mgr_flag to 'N' the record processes normally.  My question is, does anybody know where/or what process is supposed to re-set the flag to 'N'?  If I can find out where it's supposed to happen I should be able to track down our issue.  Thanks in advance for your help.