Picking project/timesheet items for invoice

I've just come back to using pERP after 4 months away. I am on 0.4 and an old problem has crept up again. When I create a new receivable invoice and bring up the pick list of project and timesheet entries, it shows me everything for that customer, including items that have already been invoiced.

I know I've seen this before, and I think Nathan had confirmed that only uninvoiced items should show up.

Any suggestions? Any reason this problem would keep cropping up?

Thanks,

Ron