The sync indicator
The cloud icon and the “No connection” banner tell you the sync state.
At the top of the sidebar there’s a cloud icon showing the state: connected/synced (green) or offline (grey). When you’re offline, a “No connection” banner also appears; when the connection returns, it shows syncing and disappears.
Support note
If, on returning, offline mode is slow to respond, a Reload button may appear — tap it to refresh the page.