Try the unresponsive Puck troubleshooting steps for Pucks.
For battery operated Smart Vents, try replacing batteries with fresh, new batteries.
Ensure your Gateway Puck(s) have a good WiFi connection.
After confirming that your Gateway Puck has a WiFi connection, turn on Setup Mode for a few minutes. To turn on Setup Mode, tap the PLUS button and select "Add new Flair Puck" or "Add new Flair Vent".
Wait up to five minutes for all your devices to enter Setup Mode. Confirm that all your Flair devices have been added to your home before exiting Setup Mode.
After exiting Setup Mode, refresh the data in the App (either by refreshing your browser or closing and reopening the App) to confirm that your units are visible.