[Q] Notification security prompt every time smartwatch reconnects to phone

I have a European Snapdragon Note 4 on the current official 5.1 update which is paired to a Garmin Vivoactive smartwatch, the smartwatch uses an app called Garmin Connect which runs on the phone and pushes anything in the notification bar to the watch. It's all worked flawlessly until the Android 5.1 update after which the phone and watch regularly lose connection and will not automatically reconnect (works fine if the watch goes out of range and comes back into range), I have to manually connect the two by opening the app, waiting for the two to connect at which point the phone pops up a warning that Garmin Connect needs access to my notifications even though it shows as having access already. Unticking, reticking then accepting the warning works but is obviously irritating when this is happening several times a day. There was an update for the Connect app today which I've applied but it's made it worse as the phone no longer prompts for the notification access, instead I have to go into settings and untick/retick again.

I've asked on the Garmin forums as well although since this only happened on the Android 5.1 update it suggests the fault is with the phone, any suggestions to get around this problem and stop having to keep resetting the notification security? I use Nova launcher which also has access to the notification panel although it's not reporting any problems.

Thanks,
John