Some users have reported issues using recommended settings from Racelab App. You must check the following. Open Racelab App and click F1 on left side, and then "Settings" and then "Connection Settings"  - Look at Port number. It must match the port number in the game.  For F1 I use port 9005 and I make sure 9005 is in Racelabs connection setting and in the game Telemetry setting. Next I use 2023 as "UDP Format in the game settings" after making these changes close game and Racelab App, and restart the computer. Next start the game first, and then Racelabs after the game.

And here is the connection setting page in Racelabs that must be checked / changed to match in game Telemetry setting udp port number