⏰ In A Nutshell
Please turn off the screen filter for the moment.
⏰ To Elaborate
Screen filter apps such as Blue Light Filter can cause this problem.
These apps provide an overlay over the phone screen, hence displaying this message. Turning the feature off will solve the issue.
⏰ Keep This In Mind
This issue is related to Android policy with overlays in Marshmallow version.
Please kindly understand that it is thus unavoidable.