The app is designed for offline-first, so you don’t have to care about the network reachability.
Notes should be always saved in the local database whenever you leave or shutdown your computer or quit the app.
So, the issue must be resolved by identifying what actually prevents your notes from being saved locally.
Oh yes, I can see that. It’s just that when you frequently work on a single document on two different devices, without any custom conflict resolution (and without frequent syncing) it’s very easy to encounter conflicts.
As for why it’s not saving sometimes, I have no clues.
If you save a note on X, the app on Y should reload the note immediately after syncing.
But if you already made some changes offline on Y, it creates a conflict.