Not sure why that is stating transmit returns, the following FAQ might help you.
How do I file an IRS extension (Form 4868) in TurboTax Online?
https://ttlc.intuit.com/community/extensions/help/how-do-i-file-an-irs-extension-form-4868-in-turbot...
I don't know but maybe file an extension outside of your account by using TurboTax Easy Extension.
https://turbotax.intuit.com/irs-tax-extensions/
---------------------------
Since we cannot get into your account or see any information, if you are still having problems you might want to contact TurboTax Support.
https://support.turbotax.intuit.com/contact/
