that's odd, somehow group is not suppressed and it overrides original one. group is always generated after original one.
Can you capture the debug log while notification is delivered - the one which is vibrating and not showing (that will be insert/remove) and the one with subsequent mail? To capture that you can use pebble sdk tool and dev connection (enable dev connection and use pebble logs --phone <phone ip>).
If you have no sdk or cannot install it - then old school ssh to phone and run daemon manually will do (need to disable service first).
I need logs after firmware update message - a section starting with watchfish:Notification Notification(sender=... up to latest line of doMaintenance: Executing maintenance cycle (with timestamps) - may need to wait till that one for up to one minute (normally) or less (if something is wrong).

A color is different for pre-defined groups of messages, and is red for unknown. Previously the same logic was applied - but it was not working properly so everything was falling to default and was red.