Yes - If you have a password set for the closing date in QuickBooks, the API will still add the bill to Method, however, the bill will not sync to QuickBooks (A conflict will be created to identify that you tried to create a transaction in a closed period).
Based on your respose, it sounds like you have transactions sync'ing over to QuickBooks for closed periods
. This should not be happening.
If this is the case, I
have our team investigate this issue for you.