League sources told NFL Media and ESPN on Friday that Cooper hasn't been practicing due to the heel injury. The wideout is working toward a return and hasn't been ruled out for the preseason, according to the NFL Network.
Cooper, along with quarterback Dak Prescott and running back Ezekiel Elliott, is asking for a new contract with the Cowboys. The pass-catcher chose to attend training camp but has been absent from practice drills, according to NFL Media.
The Cowboys acquired Cooper in a mid-season trade with the Oakland Raiders in 2018. He recorded 75 catches for 1,005 yards and seven touchdowns in 15 regular-season games between the Raiders and Cowboys.
The Raiders selected Cooper in the first round (No. 4 overall) of the 2015 NFL Draft out of Alabama. In 61 career games, he has registered 278 receptions for 3,908 receiving yards and 25 touchdowns.
Dallas has three preseason games remaining, including a matchup against the Los Angeles Rams on Saturday night in Hawaii. According to NFL Media, Cooper made the trip with the team.