Mixon, who was suspended for the 2014 season for punching a woman, is among the top five running backs in the draft based on talent, according to ESPN NFL Draft analyst Mel Kiper Jr.
The exclusion of both players was first reported by USA Today.
It is unclear if the players' off-the-field troubles were factors in their omission from the list.
In 2016, the NFL announced a policy that college players with convictions for domestic violence, sexual assault or weapons offenses would not be invited to the combine. But that doesn't necessarily apply to Mixon or Zamora.
Mixon was suspended for the 2014 season for punching a woman at a deli in Norman, Oklahoma. The incident resurfaced this past December, when Mixon's attorneys released surveillance video from the scene. The video showed the victim, Amelia Molitor, shoving Mixon and then slapping him. Mixon then punched her in the face, breaking her jaw, eye socket and cheekbone.
Mixon received a deferred sentence and community service at the time and underwent counseling.
Zamora was suspended three games and charged with a Class C misdemeanor after a Snapchat video showed him hitting his dog eight times with a belt and kicking it. Zamora was also ordered to complete 40 hours of community service and undergo counseling.
After Mixon's college career ended with a win at the Sugar Bowl, Kiper ranked him fifth among running backs, based on ability alone, behind Leonard Fournette, Dalvin Cook, D'Onta Foreman and Christian McCaffrey. However, Kiper didn't include Mixon on his latest Big Boards.
Zamora made 63 catches for 809 yards and eight touchdowns in 10 games in 2016.