its working only when the phone its not in "stand by" mode - in the daytime its work almost 100% with what you write and with other suggestions - but after 6-7 PM when i use the phone less - maybe one time per hour, gmail still not sync as it should..yesterday i receive one email at 20.48 - i didnt receive it until today in the morning
Can I get clarification on whether changing to the native Samsung email actually ''fixed'' the issue Gargamel? I'm having the exact same problem, the issue is seemingly random: sometimes emails come in, sometimes not, sometimes I get the icon appear but no sound, sometimes nothing at all.. etc.. if using the Samsung email app works I'm tempted to just use that! Not ideal but better than missing important emails..
Since this is the top result in google searching for gmail delayed notifications, I found this to fix the problem on my S9 Galaxy. I didn't come up with it, found it on a different forum. This does not require the phone to be rooted.
Basically this disables some form of deep sleep in the phone. I haven't found it affected battery life much, if at all, but I am sure that's why this feature exists.
Also, this will only disable the deep sleep feature until the phone reboots. At that time it will return or normal and you would have to re-run these commands. I don't reboot often so it isn't a huge deal for me.
Also I am running the commands from a windows PC, but any ADB client can do it.
1. Download and install the Samsung USB Driver onto your Windows PC.
2. Download and install the Windows ADB (Android Device Bridge) software from Google (just need to unzip it, no actual install procedure).
3. On your Samsung phone, go into Settings and check "Enable USB Debugging"
4. Connect your Samsung phone to the Windows PC and it should pop up on the phone and ask to allow USB debugging, you want to allow it.
5. Open a windows command prompt, navigate to the folder where adb.exe exists (where you unzipped it). Run the following commands (two separate commands):
adb devices <-- should show one entry under "list of devices attached". If it says "unauthorized" then you need to make sure and allow USB debugging. You may need to go on the phone under settings and "Revoke USB debugging authorizations" and re-allow it.
adb shell dumpsys deviceidle disable <-- this will disable light and deep idle
6. That's it, unplug the phone from the PC and you're good to go. At least until you reboot.
I have exactly the same problem on my brand new Galaxy Note10+ as described by many others in this thread. When the phone has been on standby (screen off) for 5-10 minutes or longer, it receives no notifications from Gmail. Sometimes, when turning on the screen, notifications (sound and popup) appear instantly, sometimes not - and I have to actually open the Gmail app to see if there are any new messages. The stock Samsung e-mail app does NOT solve this issue (interesting that it wasn't pre-installed, only the Gmail app, so I had to download it from Google Play Store). I tried disabling the Gmail app and setup the Samsung app instead, but it turned out to behave in the exact same way.
Someone mentioned that Gmail was "woken up" by another app, and I have the same experience. Strangely, I receive all notifications from Google Calendar and other Google services, and yesterday I noticed that at the very same time I received a Calendar notification, the Gmail notification was suddenly activated (telling me about an e-mail received two hours earlier!). This issue is driving me mad, especially after having spent $1,300 on a state-of-the art smartphone. Samsung here in Denmark are currently investigating this, but I must admit that I have little hope of any solution based on the hundreds and hundreds of similiar complaints from users around the world :-(
And yes, every single battery optimization, background data restriction anti-sleep-keep-alive setting has been disabled.
SAMSUNG, this is not OK!
Same issue with my new samsung a50 , android 9 - when i am using phone , i am getting all notifications, but when i am not using it for more then 5-10 mins , i will not get any notifications alerts , until i tap a screen , then all emails and notifications suddenly comes together.