Just appeared on the offers app, flash sale for today only until 5pm. Same as Monday's deal.
I checked 4 stores in 4 states and the offer was available at each with the same code, however if not working at your local try another store or check the offers app. It also seems to be 5pm local time from testing. You can also try the $1 Garlic bread code 486874, however that only works at the minority of stores.
Edit: Added 324777 code for those stores that don't accept 817760.
Edit 2: It appears code 817760 has changed to Offers App only. Download the Domino's Offers App here if code 324777 isn't working at your store.