Why are transactions for closed Cost Management and Payables period still importing to Projects?

Summary:

We are doing a normal period close process.

We make sure Cost Management is all closed and imported to PPM. Payables as well is closed for the current period. So these two modules should not send new transactions for current period. All new transactions should now be processed in next period. As they are both closed.

We then review any period close exceptions and try to clear them. By the next time we run the report we have new transactions for the same period from both AP and Cost Management, even though the periods are closed.

We are expecting all new Cost Management transactions to be treated as the first open Cost Management period - i,e, to be applicable to next period. Not the one we are trying to close.