@Tejaskumar_Darji,
Unfortunately, that is a limitation of the PDFSharp library. If you look at their FAQ you'll see that they do not implement all features of PDF v6 format. The only workaround, that I'm aware of, is to resave the actual PDF using the v5 format.
Cheers,
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Eric Wilson
Director, Integrations and Enablement
Blue Prism Digital Exchange
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