RadPdfViewer does not read image resources defined in Form XObject elements.
When importing a document with empty pages collection an ArgumentNullException: 'Value cannot be null.
Parameter name: page', is thrown, which leads to application crash.
Workaround: Import the document using the PdfProcessing library and add an empty page:
They are used by the page and the XObjects drawn on it and deal with the overlaying of the colors. These groups are described on page 556 of PdfReference 1.7.