I have a couple of problems too, though I don't consider them deal breakers - but number 2 in my list is the worst.
1) "Ok Google" - not. It will plain ignore me even when I'm yelling at it. I've noticed this occurs when the phone hasn't been used for a bit. It's like Assistant has gone to sleep.
2) Why won't you understand me Google Assistant? My phone is set to UK English and I've checked that's the language Assistant is using. I don't have a strong - or indeed really any - regional accent. Classic middle-England standard English, Received Pronunciation. And yet.. Assistant gets it wrong more often than right. And once it's decided what it's hearing, you can repeat it a million times, saying it ever more clearly and slowly and it won't change from its first decision. It's borderline awful and a thousand times worse than Amazon Echo (so I'd never buy Google Home frankly). This one drives me crazy. I must have tried 50 times (out of sheer stubborness to get it to recognise the word "coil" today. And failed.
3. Downloaded some new Notification sounds. Put them in Notifications folder. I can select them from Messenger and WhatsApp as the notification sound. It uses the chosen sound once or twice and then reverts back to a built-in sound (usually "Strum" for some reason). This one Google are looking into (and how cool is the built-in phone support??

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