Thanks for sharing this. I just spent 45 minutes on the phone with ProConnect support to find out that it was a local return blocking the filing. The IRS and State returns were able to be e-filed but the local return was not. Once I unchecked the E-file box for local, I was able to transmit 2017 Federal and State. ProConnect (says they are) working on updating the error message to clarify the issue. Right now the error message claims that the IRS and States are not accepting 2017 e-file, when really it's dependent on local!