Contract Closure Validation for Project Contracts

Our PPM team noticed that they are no longer receiving an error when trying to close a contract and the revenue amount does not equal the billed amount. Previously, this threw the error OKC-195355 and prevented closure with a pop up window. Now, it looks as if it is closing (no error), and doesn't actually close the contract. Has something changed that would prevent this error from popping up, and is there any control over how to make sure it is providing the warning so we can address the issue and properly close the contract?