This didn't happen with my LG G3 a while back, but it all started with my Galaxy S7 Edge.
The first time I noticed a problem was when my alarm went off maybe 30 minutes or so later than it should have. It was as if my phone was kind of "asleep." Then I noticed that if I left my phone alone for a little while (sometimes 30 minutes or an hour or so), that any notifications - email, games, whatever - would also be delayed until I at least "woke up" the phone by just turning on the screen. Sometimes I would get a dozen notifications all at once when I do that, and they didn't all actually come through at that exact time - they were delayed.
This happens everywhere and whether I am on wifi or not. It has continued with every Galaxy phone since. I currently have the Galaxy S10+. There are some apps that I will allow to sleep, but the alarm, Gmail, and Outlook are definitely ones that are not on that list.
With each new phone, I hoped that the problem would be gone, but it has continued. I obviously have gotten used to it, but I hate thinking that I can never trust the alarm or feel comfortable that I am getting all notifications in a timely manner. It came to the point today that I was searching for other Android phones to possibly change over to, though I would really prefer not to do that since other than this, I have loved the Galaxy line.
Any input would be appreciated.
There may be many reasons this happens but few things to make sure. Is you phone in any power saver mode if it is it would delay background running of apps and the Syn on gmail and other email apps. Also on email app make sure to change the setting of time they are Sync and put it to lowest time so that you get notifications faster. Also turn of any Battery Saver stuff and see if it fixes the issue in this case it would be the settings and can be changed.
If you've found my post to be helpful, please like the post. If my response resolved your issue, please press the "✓ Accept as Solution" button.
Thank you. I did find another location where there was a battery optimization mode, and these apps were optimized to sleep. I have changed those apps to not be optimized and will monitor them over the next few days .