Getting this today in the 787, with or without the Thrustmaster Airbus devices connected. Toggling AP and A/T doesn’t seem to do anything.
A/T says it’s on, shows on the HUD but completely dependent on throttle position.
Edit: Have somehow got it working from loading fresh and then toggling the right side A/P, F/D buttons, then toggling A/T Arms, and spamming the engage selected airspeed button. Do not use VNAV at any point.
Edit 2: Also noting that LNAV button is broken.