Hi Manoj,
Thanks for contacting Syncfusion support.
It seems you are using old version(4.2.0.31) Syncfusion assemblies, which is marked as legacy. So can you please upgrade your product version to latest version of Essential studio and check the conversion and let us know the result.
Also we suggest you to try our latest WebKit HTML converter for converting HTML to PDF, which has more features and enhancement than the IE rendering Engine. You can get the latest version of WebKit HTML converter from below link,
After installing WebKit HTML Converter, you will get QtBinaries and samples from WebKit installed location
(example: C:\Program Files (x86)\Syncfusion\WebKitHTMLConverter\XX.X.X.XX\).
Refer below link for more information about WebKit HTML converter,
Regards,
Prakash V