My QA team found that our push notifications to GCM aren't working on devices running 8.0 and 9.0 but still seem to working on the 5.x and 6.x test devices no problem.
The response from the GCM server seems fine for all pushes being sent out and I see no errors on the newer devices.
I know GCM is being deprecated but Google says that isn't until at least April 2019.
We have conversion to FCM on the schedule but there hasn't been time to do that yet.
Any thoughts, thanks.