Same thing for me. I called Region I office to ask what to do next, since my son's Lifetime License card was issued when he was 6 months old. They won't issue you anything new since they did it online. They only send out cards for in-person courses now. You'll need to have a screenshot of the confirmation, or they'll need to carry a printed certificate with them.
The lady at the Region I office told me that even though the RULE OF LAW isn't met by your license showing "Hunters Safety Confirmed", most officers will consider that as having proof of H/S. In order to ensure their information is synched, call your Regional office. Get your boys' TWRA numbers in front of you, and call to confirm that the Agency has recorded their completed courses. The person on the phone will have access to their records, and will be able to automatically apply their Hunters Safety records to their TWRA number. After that, you can order a replacement Lifetime Sportsman card for them, and their H/S date will be on the card.
If they've never hunted before, you may want to get online
https://www.gooutdoorstennessee.com/ and establish a profile for each of them. You can input vital records which will likely be much more up to date for their license when you call and eventually order a replacement card for them.