Hey, please everyone who have the same issue CALL samsung now and file a report, and please leave on gmail support forum ticket/complain.
"I just bought new S10e factory unlocked 2 weeks ago. Activated it 5 days ago. Overall everything seems ok, except Gmail notification!
I'm getting email notification with 5, 10, 20... minutes or hours delays, or never.
1. I searched youtube, forums, and articles, contacted samsung tech support to solve the issue
2. The issue is well known for 3 years already, since 2017 people claim the issue on different models!
3. I did and follow all ~10 possible fixes: including: sim card reinsert, restarted phone, soft reset, hard reset (factory restore), reinstalled gmail, enable all SYNC everywhere, enable all notifications in gmail setting (to constantly get notification for all emails), enable all notification in phone settings specifically and in general for gmail, removed gmail from battery optimization, tried Samsung email app, cleared all cache, etc.
4. It seems the issue so far only with gmail, other apps I think I'm getting constant notifications."
05-30-2019 12:11 PM