The activity that appears in the incorrect net asset account are balancing interfund entries.

For example:

A deposit for $7500 is posted to different funds:
DR: 10-XXXXX (Cash Account)
CR: 20-XXXXX (Revenue Account)

The system creates an interfund transfer to ensure the funds credist and debits remain in balance:
DR: 20-XXXXX (Transfer Account fund 20)
CR: 10-XXXXX (Transfer Account fund 10)

When filtering the Income Statement by Fund 20, the following transactions are shown:
CR: 20-XXXXX (Revenue Account) +$7500
DR: 20-XXXXX (Transfer Account) -$7500

Both fund 20 Income Statement accounts close into the net asset account, which results in a wash.

When filtering the Income Statement for fund 10, only the credit to the transfer account (10-XXXXX) will appear. This is becasue the debit transaction (10-XXXXX) for the deposit is to an asset or Balance Sheer account. This results in the report appearing to shwo fund 20 closing into fund 10.