IThumbnailProvider doesn't work with IInitializeWithFile - Initialize is never called

I took the RecipeThumbnailProvider sample and tweaked it to implement IInitializeWithFile intead of IInitializeWithStream, but Iinitialize is never called.

I added a registry entry to disable process isolation. Documentation here says to do it this way:
{HKEY_CLASSES_ROOT, L"CLSID\\" SZ_CLSID_RECIPETHUMBHANDLER, L"DisableProcessIsolation", L"1"},
But I also tried with this:
{HKEY_CLASSES_ROOT, L"SOFTWARE\\Classes\\CLSID\\" SZ_CLSID_RECIPETHUMBHANDLER, L"DisableProcessIsolation", L"1"},

I happened to fail to update the Query interface when I first tried this, so it looked like this (note I'm referencing IInitializeWithStream):

    IFACEMETHODIMP QueryInterface(REFIID riid, void** ppv)
    {
        static const QITAB qit[] =
        {
            QITABENT(CRecipeThumbProvider, IInitializeWithStream),
            QITABENT(CRecipeThumbProvider, IThumbnailProvider),
            { 0 },
        };
        return QISearch(this, qit, riid, ppv);
    }

With this code, Initialize IS called, but the file path is empty. When I update the query interface to reference IInitializeWithFile, Initialize isn't called at all.

In my google searches it seems like other people have run into the same issue w/no resolution. I have not been able to find a working sample. Any chance of getting some working sample code?

Start with the RecipeThumbnailProvider sample, its QueryInterface implementation, and the DisableProcessIsolation registry entry described in the issue. Compare the IInitializeWithStream and IInitializeWithFile paths and verify which interface is queried. Done means a working sample invokes Initialize with the expected file path.