First, try trashing PT preferences.
Set the buffer size appropriately for the Sample Rate. In Pro Tools, the available Buffer Size settings varies depending on the Sample Rate.
Start the app with the “N” key pressed down. This will initiate the playback engine before every other instance of PT and switching the driver at this point may solve the issue.
Only for OSX – Create an Aggregate device in the Audio MIDI settings → choose the Antelope device to be in the aggregate → start app with the “N” key pressed down and choose Aggregate device.