Thanks for clarifying !
The "Speedometer" ( whether digital or analogue ), displays the speed
of the motorcycle across the ground in Miles or Kilometres per hour.
The "Tachometer" displays the operating speed of the engine in Revolutions per minute.
( There is no Digital Tachometer display - other than on connected Diagnostic equipment ).
The Trophy digital speedometer display IS known to be affected by low climate temperatures.

There are several reports throughout the Forum of the Digital Speed not displaying
when the temperature is low - typically anywhere below 4 or 5 degrees Celsius,
but always resumes when the temperature warms up, so that is almost certainly
the issue you are experiencing, and is nothing to worry about,
although no-one
really seems to know why it happens !
Cheers
