The app isn't working or is showing errors. Clear your device's cache and reinstall Yandex Pro from Play Market. If that doesn't help, describe the issue: what are you tapping and what's the error message? We can help you better if you attach a screenshot.
Navigator keeps losing signal. Geolocation normally works better after doing the following:
— Activate power saving mode
— Connect to Wi-Fi
— Close all other apps
— Check your GPS module configuration with a GPS testing app
If nothing helps, message us and we'll figure it out together.