Trying to paste an image from Snip & Sketch (the Snipping Tool replacement from Windows 10 October 2018 Update aka RS5) results in nothing happening.

Looking through the code I found this to be the root cause - ImageData is only created if there's a DIB in the clipboard. It does work with the Photos app because that one also puts an image file in the clipboard, which OLW is able to treat as image content, but it seems like it wouldn't work with most modern (UWP) apps that just call the standard DataPackage::SetBitmap()

/// <summary>
/// Image Data contains Image data that was parsed from the DataObject.
/// </summary>
public class ImageData
{
    /// <summary>
    /// Creates an ImageData
    /// </summary>
    /// <param name="iDataObject">The IDataObject from which to create the ImageData</param>
    /// <returns>The ImageData, null if no ImageData could be created</returns>
    public static ImageData Create(IDataObject iDataObject)
    {
        if (!OleDataObjectHelper.GetDataPresentSafe(iDataObject, DataFormats.Dib) && !OleDataObjectHelper.GetDataPresentSafe(iDataObject, DataFormats.EnhancedMetafile))
            return null;
        else
            return new ImageData(iDataObject);
    }

It starts working correctly if I change it to:
public static ImageData Create(IDataObject iDataObject)
{
if (!OleDataObjectHelper.GetDataPresentSafe(iDataObject, DataFormats.Dib) &&
!OleDataObjectHelper.GetDataPresentSafe(iDataObject, DataFormats.Bitmap) &&
!OleDataObjectHelper.GetDataPresentSafe(iDataObject, DataFormats.EnhancedMetafile))
return null;
else
return new ImageData(iDataObject);
}

Really though - it should check for all supported image types before giving up.