USCIS has provided a helpful guide explaining how employers should handle an E-Verify TNC (Tentative Nonconfirmation). USCIS sent out the guide via email - if you would like to receive future updates from USCIS (that might not be posted to their website), you can subscribe to their email list here. While the guide itself has not been posted to the E-Verify website, it basically follows the instructions laid out here.
If you would like a copy of the TNC guide that was emailed, just reach out to me at aimee@clarkimm.com.