Array<> deallocated too early by WinampBar

In a WinRT component project, I have an async operation which takes an array as an argument. Although captured, the array seems to have been deallocated when the worker lambda gets to touch it.

static IAsyncOperation<int>^ SumNumbers(const Array<int>^ numbers)
{
    return create_async([numbers] ()->int {
        int sum = 0;
        for(unsigned int i=0; i<numbers->Length; ++i)
            sum += numbers[i];
        return sum;
    });
}

This causes an access violation when 'numbers' is referenced within the lambda, and debugging printout does show that the variable is indeed garbage.

Changing it to create a copy of the input array, as in:

static IAsyncOperation<int>^ SumNumbers(const Array<int>^ numbers)
{
    auto numbers2 = ref new Array<int>(numbers);
    return create_async([numbers2] ()->int {
        int sum = 0;
        for(unsigned int i=0; i<numbers2->Length; ++i)
            sum += numbers2[i];
        return sum;
    });
}

does work, but with an extra copy of course.

Should capturing 'numbers' in the lambda environment increment the reference count to keep the variable alive for the lambda to process?