Hi there,
I just want to inform you in my case I do not receive anymore the notifications on my mobile phone (gDMSS Plus) when someone rings on the door.
It looks to be a general issue Dahua must solve after Google has changed the push service , see reply from my vendor :
This afternoon it has been revealed that Google has changed the push service for a number of Android versions and this has impact on a large part of the Android devices using IMOU or GDMSS.
This implies that Dahua must solve it, just Dahua is currently celebrating Chinese New Year, which makes the solution just waiting a bit longer.
Hope it can help you if you are in the same situation.