FlymeOS 8.0.0.5A : No GCM Notifications

Describe the bug
Hi,
I installed the latest MicroG from Fdroid (0.2.19.211.515) and I disabled all the battery optimizations in the FlymeOS security center but still no FCM notifications.
The apps registers fine but as I see the GCM got disconnected once i close the MicroG settings panel and open it again.
If i leave the MicroG settings panel in the foreground i can get notifications so I think it is related to FlymeOS because it worked fine on AOSP-Extended.
(I used the "push notification tester" app from AuroraStore to make the tests).
(I installed the spoofing signature support via "nanodroid-patcher" TWRP script).
All the MicroG auto-verification checkboxes are enabled.

I really like Flyme OS and I want to keep it installed so how i can fixe this notification bug?

Expected behavior
FCM does not disconnect when MicroG settings panel is not in the foreground.

System
Android Version: 7.1.2
Custom ROM: FlymeOS 8.0.0.5A
MicroG: 0.2.19.211.515

No source file or test is identified in the report. Reproduce the disconnect on FlymeOS 8.0.0.5A by registering an app, closing the MicroG settings panel, and using the Push Notification Tester; done means FCM remains connected and notifications arrive while the panel is not foregrounded.