When column base_invoice_price_variance and invoice_price_variance in ap_invoice_distributions_all a

 Hi everyone,

I have a question about a kind of strange case in our AP.  We have a PO with 4 lines and one of them has $250 (total is $1200).  The unit price for this line was adjusted to zero at some point, and I can see the reversal of the $250 in GL.

However, an AP invoice was created for all 4 lines and matched to the PO.  System took it somehow and columns base_invoice_price_variance and invoice_price_variance were populated with amount of $250 for the cancelled PO line.  This invoice line was not transferred to GL.

I just wonder why an invoice was allowed to match to the PO line with zero amount?  In the future, how we can prevent this from happening again?