Calling IWICImagingFactory.CreateStream simply never succeeds: it crashes with either an access violation or a null reference exception. This might be a regression, since I don't remember having issues like that with an earlier version of Vortice (it was probably 1.8.x).

Here is a repro project, but really it's just 3 lines of code:

using FileStream stream = File.OpenRead("LuLu.png");
using var wicFactory = new IWICImagingFactory();
using IWICStream wicStream = wicFactory.CreateStream(stream);