Hello! I've waited a while to report this since I wasn't sure if it would just go away on its own, but after several weeks I'm still facing the same problem, all my apps that rely on GMS for notifications don't send any, even if Play Services is installed and enabled.
I did read somewhere that any app that would need it had to be reinstalled after I had installed Play Services, so I did try with Discord in particular, but it didn't change anything.
These are the apps I use where I've seen this happening in:

  • Discord
  • Proton Mail

These ones send notifications on their own only if I keep them in the background with battery optimization disabled, but that of course affects battery life quite a bit:

  • Instagram
  • WhatsApp

What should I do to make them work?

Does Play Services have background data usage set to Unrestricted?

    Probably9857 It does not need background data unrestricted but Battery Usage Unrestricted.

    Also Google Play Services must be installed b e f o r e the apps that depend upon them are installed.
    At least this works in my case :)

        FlipSid

        Battery Usage Unrestricted

        Yes, it already is like that.

        Also Google Play Services must be installed b e f o r e the apps that depend upon them are installed.

        As I said, I did do that for Discord, but it still didn't work. As for the others, I'll try again with Instagram and Proton Mail since I checked and they were installed earlier than the Play Services, I'll update and say if they worked or not

            SappySyrup after that wie can check your permissions.
            I've had the case, on a side note, that I uninstalled GS, after that notifications where gone for proton mail.
            I had to uninstall all apps that depend on GS, reinstall google play services and then reinstall all apps that depend to get it to work again :)

                I guess I can try reinstalling everything, but I don't understand how that would work to make a difference, do you have a hunch? Also I have never uninstalled the Play Services as you did, so things shouldn't have broken along the way (theoretically).

                Btw, by now I can report that both apps still don't send notifications, so the current setup just doesn't work for some reason.

                FlipSid after that wie can check your permissions.

                Ah, almost missed this, what should I look into for permissions?

                    SappySyrup are you running other google apps?
                    Since I do I have enabled:
                    Notifications
                    Contacts
                    Network
                    Sensors
                    SMS
                    If you don't probably Notification/Network/Sensors should be enough. Maby someone else will chime in too

                        FlipSid

                        are you running other google apps?

                        No, aside from the Play Store and Google that I don't use

                        If you don't probably Notification/Network/Sensors should be enough.

                        You're right! I had no permissions enabled for Google Play Services, that's a big oopsie on me, I just assumed the basic ones would be there by default.
                        Now I enabled Network and Notifications, I'll see if something different happens now, looking at their nature, nothing could have worked before, that's for sure

                          Ok, I can confirm that with those 2 permissions enabled now everything works as it should, thanks for the help!
                          And while we're here, happy holidays!

                          FlipSid

                          It does not need background data unrestricted

                          Play services does need unrestricted mobile data usage to be on if Data Saver is on.