Hey @Sorin. We do have a list of apps that conflict with the Ring app, as well as a troubleshooting guide when the notifications do not come through on Android. Please check these out and let me know what you were able to do to reach a resolution, or if it still fails, let me know what you did in addition!
Thank you very much for the reply. The issue is solved now.
When I saw your answer and the apps related to the battery saving (Battery Plus, Battery saver, etc)I realized that the issue may be related to the “App battery saver” where I selected “No restrictions for the Ring app”. This is a typical Xiaomi setting I assume, I hope this will help others as well.