When corporate contributors are added to the approved list or they complete CLA signing process, the CLA status still remains Not Covered for GitHub, and shows No Contributor Agreement for Gerrit while submitting change.
After you are added to approved list, you must acknowledge company contribution or sign ICLA if your CLA requires you to sign individual CLA for getting full authorization to contribute.
Navigate to Gerrit window, sign out and sign in again, and then submit a change.