I didn't get any notification after I updated my phone into Android 8.0 (I'm using MiA1)

I played SSSM before in my tab (since my old smartphone is running out of memory). I always got notification about it, at 12PM KST, 4PM KST, anytime when they sent it. But after I played in my smartphone (Mi A1), first of all the logo of notification is just showed a grey-round with no logo of it. But still, there's notification. But, after I updated into Android 8.0, no notification at all. I checked on my setting, but it just right. Anyone can solve this?

I played SSSM before in my tab (since my old smartphone is running out of memory). I always got notification about it, at 12PM KST, 4PM KST, anytime when they sent it. But after I played in my smartphone (Mi A1), first of all the logo of notification is just showed a grey-round with no logo of it. But still, there's notification. But, after I updated into Android 8.0, no notification at all. I checked on my setting, but it just right. Anyone can solve this?

http://ift.tt/eA8V8J