Your truck is operating as it should.
At idle, you get 0 miles per gallon, or essentially infinite liters per kilometer, which is what you're seeing. You're not moving, but the engine is still using fuel.
A US truck will show 0 miles per gallon (infinite gallons per mile) at idle, which will then slowly climb upwards as you reach steady state speed. As a Canadian truck is the opposite, reading in liters per kilometers, you'd see 99 at idle - the highest that the EVIC can display. This would then drop to a normal number as you accelerate and reach steady state.
Matt || 2013 2500 Laramie || CCSB 4x4 CTD || Maximum Steel || Nitto Terra Grapplers 305/70-17s