No On-Screen Data On Transmitter after 3.3.1 Update

I recently updated on of our 3DR X8+ machines to Arducopter 3.3.1. After the update, I no longer receive telemetry data on the display of the transmitter. When I downgraded back to 3.2.1 it started working again. Does anyone know a fix for this?

Did you read the release notes:

Note #3: set SERIAL2_PROTOCOL to “3” and reboot the board to enable FrSky telemetry like in previous versions.


I strongly suspect that @iseries’s answer is correct so I’ll mark this as closed if that’s ok.

BTW, the other common cause of no telemetry data on the OSD is the OSD itself is not asking the flight code to send telemetry data. This can be resolved by clicking the “Enable Telemetry” button on the MP’s InitialSetup >> Optional Hardware >> OSD screen.