Hi,
Have you check any update of firmware or a system update for your Lenovo device? You can try checking for an update as the first step to check if the problem will be resolved.
If the update won't fixed the problem, try a factory reset. Factory reset will erase all user data and reset all settings to the manufacturer default, including deleting all user-installed apps and restoring built-in apps.
Go to Settings > Backup & reset.
Tap Factory data reset.
Check the backup dialogue box, then tap Reset phone and tap Erase everything. Wait for few minutes for your phone to restore to factory setting.
Let me know if this step worked. Thanks!