Invalid code generated for nullable conversion to IntPtr?

[cston]

using System;

class Program
{
    static System.IntPtr Convert1(double? value)
    {
        return (System.IntPtr)value;
    }

    static System.IntPtr? Convert2(double? value)
    {
        return (System.IntPtr?)value;
    }

    static void Main()
    {
        double? d = 42;
        Console.WriteLine(Convert1(d));
        Console.WriteLine(Convert2(d));
    }
}

Result:

> c.exe
42
11529392

It looks like the IL generated for Convert2 is missing a conv.i8 when compared to Convert1.

Note: this issue is referenced in test code

[cston]

Similar issue with decimal, although in that case the generated code for Convert2 is missing a call to decimal.op_Explicit(decimal):

class Program
{
    static System.UIntPtr Convert1(decimal? value)
    {
        return (System.UIntPtr)value;
    }

    static System.UIntPtr? Convert2(decimal? value)
    {
        return (System.UIntPtr?)value;
    }
}

[cston]

Another example where the conversion is dropped. And in this case, an assertion fails in LocalRewriter.MakeLiftedUserDefinedConversionConsequence() as well.

class Program
{
    static char? Convert(System.IntPtr? value)
    {
        return (char?)value;
    }
}

[jcouv]

When trying on (sharplab), I'm getting an exception from Convert2:

42
System.InvalidProgramException: Common Language Runtime detected an invalid program.
   at Program.Convert2(Nullable`1 value)
   at Program.Main()