All notifications and prompts are blocked by default in the kiosk mode.
You can enable the status bar in the kiosk policy and see the notifications there. For this, please navigate to Android Kiosk Lockdown->Peripheral Settings->Display. Check the ‘Enable status bar’ option.
Please note that if the ‘Power Off’ option is disabled, the notification area will retract automatically. Also, this won’t be work if you have checked the ‘Disable system bar’ option (in rooted device) or disabled the status bar in Advanced Restrictions.
Kindly use the help link for more insights into peripheral settings.