Embedding files in a specific order within a PDF can cause an issue when accessing the embedded files in Adobe Acrobat.

When inspecting the main PDF in Adobe Acrobat and attempting to open a specific embedded file, the following dialog is displayed:

Workaround

Embedding the files in a different order may prevent the issue from occurring and can serve as a temporary workaround.

Import the document with RadSpreadProcessing and export it PDF format. You will notice that the cell value is displayed in the exported PDF document while in the Excel file it is hidden due to the custom format:

Currently, a NullReferenceException is thrown because of the incorrect structure. 

As a workaround, the exception can be handled using the Handling Exceptions mechanism.

Update:
When importing documents with invalid structure of path construction operators an InvalidGraphicOperandsCountException is thrown which could be handled using the Handling Exceptions mechanism.

PdfFormatProvider provider = new PdfFormatProvider();
provider.ImportSettings.DocumentUnhandledException += this.ImportSettings_DocumentUnhandledException;

private void ImportSettings_DocumentUnhandledException(object sender, DocumentUnhandledExceptionEventArgs e)
{
    if (e.Exception is InvalidGraphicOperandsCountException)
    {
        e.Handled = true;
    }
}

SkiaImageFormatProvider: Rectangle behind text overlaps the text of previous line.

RESOLVED: The issue is dismissed. The actual reason for the results is missing FontsProvider implementation. In order for accurate calculations and measurements the fonts used in the document need to be resolved correctly.

Handle import of documents with wrong type of action key.

Once this is completed use the Exceptions Handling mechanism to handle this scenario. For instance:

private void ImportSettings_DocumentUnhandledException(object sender, DocumentUnhandledExceptionEventArgs e)
{
    if (e.Exception is InvalidActionException)
    {
        

As a result of the below missing operator, some of the glyphs can't be extracted from the CFFFontTable and the characters are not displayed in the PdfViewer:

The end user result is missing letter from the PDF content.

Encoding table headers are preserved when creating subsets.

NullReferenceException is thrown when Find API is used on a newly created document.

Workaround: Export - Import the document before using the Find API

PdfFormatProvider pdfFormatProvider = new PdfFormatProvider();
byte[] exportedDocument = pdfFormatProvider.Export(document);
document = pdfFormatProvider.Import(exportedDocument);