No payment block with non-valuated GR?

Hello gurus,

in our system, tolerance key PP is maintained to automatically set a payment block for the invoice, if the amount in PO and invoice differs too much.

Unfortunatelly, the payment block is created for items with valuated GR only. For items with non-valuated GR, there is no error, no warning, no nothing.

Any ideas on this?

Thanks

Alicia