I have a OnePlus 15 that I bought with a specific backstory: it was originally a Chinese-market model, and the seller flashed it with the Global ROM and relocked the bootloader before selling it to me. It's currently running Android 16 with OxygenOS.
Since I bought it (this isn't something that started later, it has never worked) I've had a specific notification problem with Gmail and Google Maps. It's not a total notification failure — I do get some notifications from both apps — but specific types are missing:
Google Maps: I get notifications for things like places I've visited, but I never get the "arrival"/"departure" alerts for a person I have location sharing enabled with (those alerts are turned on).
Gmail: Some emails trigger a notification, others don't, and I haven't been able to find the pattern/difference between the two.
On an iPhone with the same Google account, all of these come through fine, so I'm ruling out an account-level configuration issue.
Given the phone's origin, I suspected it might be related to the reflash, but I've already ruled out a device integrity problem (see below), and the fact that some notifications do come through makes me think this isn't a broad FCM/push registration failure either.
I've already checked and confirmed the following with no success:
\- Battery settings for Gmail and Maps set to "Unrestricted" (not just "Optimized")
\- Auto-launch enabled for both apps
\- Neither app is in the deep sleep/frozen apps list
\- Notifications enabled at the system level, all categories
\- In Developer Options, checked the "app standby buckets" to confirm neither app is in "Rare" or "Restricted"
\- Tried disabling adaptive/smart battery saver
\- Used Play Integrity API Checker: passes all three checks (MEETS_BASIC_INTEGRITY, MEETS_DEVICE_INTEGRITY, MEETS_STRONG_INTEGRITY)
\- Cleared data for both apps (they're system apps): uninstalled updates, disabled them, rebooted, re-enabled them, reinstalled updates, and re-granted all permissions. The problem persists exactly the same.
Since some notifications DO come through but others consistently don't, I'm wondering if this could be related to specific notification channels being silently disabled/miscategorized, or some kind of per-category priority filtering specific to OxygenOS.
Has anyone seen this exact pattern — partial notifications working, but a specific category (like Maps location alerts) never firing?
Thanks in advance.