It's not a bug. See my answer to your separate post of the same question.
For the benefit of others following this thread, here is the answer again.
Entering the federal extension payment does not check the box on the New Jersey return. You have to at least start to file a federal extension in TurboTax, even though it's actually too late to file it. Of course, you won't actually file the extension. You don't even have to complete it.
Go to:
- Federal Taxes
- Other Tax Situations
- Other Tax Forms - File an extension
After you answer Yes on the first two screens, saying that you want to prepare an extension, the federal extension box on the New Jersey return will be checked.
