Push notifications still doesn’t work

Hello,

I apologize for the late response. This is the site: https://smart-websites.cz.

1. Firebase credentials are set.
2. In the plugin administration I enter a test push notification – http://prntscr.com/pjj344.
3. On my mobile phone will appear the message “This site has been updated in the background” instead of typed text – http://prntscr.com/pjj3xi.
4. I create a push notification in the post administration – http://prntscr.com/pjj4fo. A confirmation is displayed, but the push notification will not appear.

Thank you for your support.