I have a Huawei P9 with the same issue.
Try this as it worked for me.
Settings
Google
Apps connected
Then disconnect any apps that might be using the mic all the time.
I had 'Google sing' and some other Google game related crap.
I disconnected them both and so far so good.
Worth a shot...
None of the above work!
I have just bought a Huawei P9 and cannot receive any push notifications until I actually open the app. I have done all the above and more.. but nothing. Very disappointing.