"Type ‘UiPath.CV.CvDescriptor’ is not defined "facing issue in validating the workflow

Facing Validation error in CV scope.
Tried even downgrading the version

AI.Computer vision version: 19.8.0 ce
UIPath.UIAtutomatio version: 2.1.0
UIPath version: 2019.8.0

Please guide us in process to overcome the validation error