Click on the '>' button next to 'Session Parameters'.From the Quick Start menu, choose 'Create Blank Session'.

Double-check your input and output settings in the Mix window of Pro Tools to make sure that they're now set correctly and test your input/output again.

The input and output paths for your audio interface should now be set to the default settings.

Click on the Input tab and then the Default button again.

Click on the Default button towards the bottom left corner.

By default, you'll be on the Output tab.

Make sure your audio interface is selected as the Playback Engine.

If you are unable to get input into or hear output from Pro Tools the following troubleshoots may fix the problem.

Click on the Apple menu in the upper left corner of your screen.

To access System Preferences in OS X, do the following:

Deleting Pro Tools Preference, Workspace, and WaveCache files.

Disable Automatic Graphics Switching (For laptops only).

Disable Sudden Motion Sensor (For laptops only).

For best possible performance, it is recommended that you do the following: Pro Tools can be affected by system settings and other software and hardware installed on your computer. Mac Guide - Mac OS X 10.12 Sierra Optimizations and Troubleshooting

Mac os 10.12 assign apps to desktop