Mayfield didn't take part in Wednesday's walkthrough due to knee and right biceps injuries, Jenna Laine of ESPN.com reports.
Mayfield was among a number of key skill-position players that were held out of drills to begin Week 5 prep -- the others being RB Bucky Irving (foot/shoulder) and WRs Mike Evans (hamstring) and Sterling Shepard (foot). Meanwhile, WR Chris Godwin (ankle) emerged from his first game action since last season as a full participant Wednesday. Mayfield was limited in all three sessions last week due to a right biceps injury, so the addition of the knee issue indicates he's a bit more banged-up this time around. He'll have two more chances to practice this week to prove his health ahead of Sunday's contest at Seattle.