Try the following scenario:

• In MS Word, create a table with text in every cell
• In the RadRichTextBox, create a new document
• Activate Review/Track Changes
• Add some empty paragraphs or some text: change tracking markup will be displayed
• Just after the inserted text, copy and paste the table from MS Word: none of the cells has change tracking markup
• If you type inside the table, the new text has markup, but the text that was pasted with the table has no markup.
• If you use the right arrow on the keyboard to exit the change tracking tag, then if you paste the table, it seems to work correctly.

No visual cue when image deleted or inserted when "Track changes" is activated. 

When inserting an image with the Track Changes option toggled, the image should be underlined with red and it isn't. When deleting an image with Track Changes on, it is also not crossed with red. In both cases, the only mark that a change was made is the vertical line on the left.

Exception when importing a document with an empty table.

Workaround: Remove the empty tables:

DocxFormatProvider provider = new DocxFormatProvider();
var doc = provider.Import(File.ReadAllBytes(@"C:\Users\mpc\Downloads\22-51.docx"));

foreach (var section in doc.Sections)
{
    var tables = section.EnumerateChildrenOfType<Table>();
    foreach (var table in tables.ToList())
    {
        if (table.Rows.Count == 0)
        {
            section.Blocks.Remove(table);
        }
    }
}
radRichTextBox.Document = doc;

1. In MS Word, create a table with text in every cell, but just before the table, add a paragraph with text (you cannot reproduce the problem with an empty paragraph)
2. In the RadRichTextBox, create a new document
3. Activate Review/Track Changes
4. Copy and paste all the content from MS Word >> as a result none of the cells in the table has change tracking markup
5. If you copy only the table from MS Word (without the non-empty paragraph), it is working as expected

Having two mention providers and using the second right after using the first one actually loads the source of the first provider.