Re: Gmail Notifications?
I started having this issue on my Galaxy Note 5 around the same time I unlocked it and flashed a custom ROM (after running stock for 5 months). At first I thought it was a kernel issue since I had tweaked some settings to try an extend battery life and lower WiFi power drain, but no matter what I did, including reflashing various ROMs, I had no luck.
After finding this thread today, I decided to uninstall the updates to the built-in Gmail app, and then use Titanium to delete the system one. Within seconds of uninstall updates, my notification shade filled up with notifications from the 7 Gmail accounts I have on push. Which led me to believe some recent updates are causing the headaches, even through I read an article last week saying Google acknowledged the issue and it was a server-side fix not requiring an app update.
I proceeded to delete the system app, reboot, and install the latest from the Play Store. All my notifications are coming in just as instantly now. Hopefully this fixes it! I did not change any sync settings or remove and add my accounts back.