SSM 48336 - 2019 Various Vehicles - Audio Voice Prompt Concerns While Providing Directions: Some 2019 F150, Ranger, Continental, Edge, Nautilus, Mustang, Fusion or MKZ may experience voice prompts that skip, hiccup or have short pauses while directions are being provided. No repairs should be made to attempt to correct this condition. Engineering is currently investigating the concern. Monitor Oasis for updates.
It's a known issue and the SYNC 3.4 update should be out sometime this month and should correct that problem.