Using the attatched file and converting it to PDF using Aspose Words for .NET version 220.127.116.11, the image turns black/gray. This has worked before, probably in 18.104.22.168
Thanks for your inquiry. Please note that Aspose.Words mimics the same behavior as MS Word do. If you convert your document to PDF by using MS Word, you will get the same output PDF file. I have attached the MS Word output PDF file with this post.
Please feel free to ask if you have any question about Aspose.Words, we will be happy to help you.