Well there are times everyone is offline. On the airplane, when switching your phone, in jail, … just think about it 
After a few weeks with my workaround (additional notification path / bypassing HA companion app) I tend to say: the workaround failed. Because: during the day when my receiving devices (iDevices) are online, I receive notifications twice or even more. Gets quite annoying sometimes.
- before: no notification at all (during night when in flight mode) → bad
- now: multiple notifications during the day → bad
Therefore:
- Can we please further track down this? (Basic notifications via HA Companion app issue: not received if devices not online - #7 by e-raser) So:
- Is it a bug or “working as intended”?
- Do I need to raise an issue on GitHub for this (not sure about that)?
- Optimizing the workaround: how to check, if a notification device (service
notify.mobile_app_something) is actually reachable / currently able to receive notifications?
I would then let Home Assistant check this first and decide if it needs to bypass the default notification path (HA companion app) or not.