Negative values in TL_QUANTITY on TL_COMPLEAV_TBL

PeopleSoft V9.2 / People Tools 8.60.11 / PUM Image 48 / T&L and Base Benefits Leave Accrual

We've run into negatives occasionally, but with year-end processing (specifically, the last accrual period for the year), we've encountered a lot of negative values in the TL_QUANTITY field on the TL_COMPLEAV_TBL record. We have not been able to identify a reason for the negatives. Any idea where they may be coming from? They're happening on all leave plans to people across the system.

I know, we should switch to Absence Management, but until management decides to do that, I would appreciate any insight into the issue