Mack signed a two-year contract Thursday with Italian club Olimpia Milano, Eurohoops.net reports.
Mack will not be available Tuesday against the Cavs due to a personal matter.
Mack is listed as inactive for Friday's game against Washington.
Mack had zero points (0-2 FG, 0-2 FT), one assist, and one steal in 12 minutes during Monday's 99-90 loss to the Pacers.
Mack will be available to make his Hornets debut Monday against the Pacers, freelance sports writer Mark Montieth reports.
Mack was claimed off waivers by the Hornets on Sunday, Shams Charania of The Athletic reports.
Mack was dealt to the Hawks on Thursday in exchange for Tyler Dorsey, Adrian Wojnarowski of ESPN reports. Mack will be subsequently waived.
Mack finished with 19 points (8-15 FG, 3-3 3Pt) a rebound, nine assists and two steals in 36 minutes Friday against Charlotte.
Mack will start Friday's game against the Hornets.
Mack managed 14 points (5-8 FG, 2-3 3Pt, 2-2 FT), five assists, three rebounds, and one steal in 26 minutes during Saturday's 119-90 loss to the Raptors.