When a payment is created and includes a benefit, there are GL distributions created for the payment itself, as well as separate distributions for the benefit. When the payment is posted and adjustment is made, the payment and the benefit are both reversed to account for this adjustment. However, while there are then positive debit and credit transactions to re-add the payment with the correct/adjusted values, there are no corresponding transactions created for the benefit, so in the post file it only appears to be reversed, but not re-added. This only occurs if the adjustment is made via a revenue update batch.
Download and install the latest patch, which contains all fixes from previous patches. If you are running an older version, download and install the latest version and then the patch.