I have the latest ImageMagick and InkScape installed on Windows 10.
Converting SVG source images sourced from FontAwesome Free works fine in Visual Studio 2022 Release mode.
In Debug mode writing to a Blob fails with the exception:
no encode delegate for this image format
auto img = std::make_unique<Magick::Image>();
auto source_blob = Magick::Blob(svg_source.data(), svg_source.size());
img->read(source_blob);
img->extent(icon_size, MagickCore::GravityType::CenterGravity);
img->magick("png");
auto target_blob = Magick::Blob();
img.write(&target_blob);
Addressing comments:
Both Debug and Release builds of my project is configured to link to the Release mode development libraries packaged with the ImageMagick install.
Since the Release build of my project works correctly the ImageMagick delegation to Inkscape works.