Ducati MULTISTRADA 1200 ENDURO Owner's Manual page 175

Hands Free (HF) Key not acknowledged
The activation of this "warning" indicates that the
Hands Free system does not detect the "active key"
near the vehicle.
Note
In this case, Ducati recommends making sure
that the active key is nearby (and that it was not lost)
or that it works properly.
Fig 83
173