List of Incompatible Phones and Potential Fixes

Brand	Model Name	Compatibility Issue	Reference Issue	Issue Fixed
Huawei	P Smart (FIG-LX1)	User reported battery 30% draining with pRMT app substantially, heavier	RSD-96 - Getting issue details... STATUS	Not sure it is anything beyond the expected level of battery drainage.
Sony	Xperia	Scanning issues with this phone's camera & some problem with the QR code or library	RSD-38 - Getting issue details... STATUS	Fixed: (this should no longer be a problem on the new QR Code)
Samsung	A6	Phone was reportedly not receiving notifications even though we have acknowledgements in Firebase	RSD-158 - Getting issue details... STATUS	Fixed: Turns out it was reported as a Mistake. It was not an A3 but a Huawei 10 phone which is also now receiving the notifications so seems no issue here really. Still not sure about the A6 though. A3 and S6 reported in RSD-158 are both working
Xiaomi	mi A1, note4	aRMT notifications doesn't sound

Potential Fixes

For Huawei Devices

Please see the comment here on how to configure for Huawei devices - RSD-96 - Getting issue details... STATUS which lists the following steps -

You need to disable the automatic management of Apps done by Huawei by following -

1. Go to Settings
2. Go to Battery
3. Go into App Launch
4. Disable The RADAR-Questionnaire App (also the passive app)
5. Manage Manually dialog will pop-up
6. Make sure all options are enabled and click OK.

Do this for all the apps including pRMT, aRMT and Fitbit.

For Xiaomi Devices

Please take a look at this post here https://dontkillmyapp.com/xiaomi

For All Devices

As stated here - https://firebase.google.com/docs/cloud-messaging/android/receive#restricted

For (Android P or newer)

Starting Jan 2019, FCM will not deliver messages to apps which were put into background restriction by the user (such as via: Setting -> Apps and Notification -> [appname] -> Battery). Once your app is removed from background restriction, new messages to the app will be delivered as before. In order to prevent lost messages and other background restriction impacts, make sure to avoid bad behaviors listed by the Android vitals effort. These behaviors could lead to the Android device recommending to the user that your app be background restricted. Your app can check if it is background restricted using: isBackgroundRestricted().

Thus make sure to remove the aRMT (and pRMT too) from the background restriction in the android device otherwise they will not be able to receive Notifications.

For Garmin Device issues with Huawei Phones

https://support.garmin.com/en-US/?faq=3qBFoCgeH428IUUfc0SpZ7

https://consumer.huawei.com/in/support/content/en-gb00411002/

https://www.solvemix.com/index.php/en/year-2018/huawei-p20-pro-cannot-connect-to-garmin-fenix.html