CLA Already Signed but PR Still Asks for Signature
Cause
The email configured in your local git config when committing does not match the email on your GitHub account, so the signature is not recognized. Check with:
git config user.email
Fix
For how to configure git, see is-it-possible-to-have-different-git-configuration-for-different-projects
After setting the correct email, recommit existing commits with the new configuration for the change to take effect.