iTasks compile can't solve overloading when using StdOverloadedList.Diag2

In this program the type of the arguments and result should be defined unambiguously:

import StdOverloadedList

Start :: [(Int, Int)]
Start = Diag2 [1] [2]

Still the compiler reports:

Overloading error [StdOverloadedList.dcl,396,diag2_]: internal overloading of "_nil" could not be solved for: List _ a (contains type variable not in function type at _ )