Hydration Notifications

My question is: Are you receiving hydration notifications correctly?

Personally, I do not receive the notifications correctly.

Sometimes they come every hour, other times I don't receive any notifications until I open the app, even though the settings are always the same.

I also downloaded and paid for the app -> apps.garmin.com/.../b217f19e-8bdf-4d6c-a3c9-def8b31e9f56

and the exact same thing happens.
What could this depend on?