Hi Mohamed,
Thank you for contacting Syncfusion support.
We are unable to reproduce the reported issue with the provide details in v18.1.0.55. We have created sample for the same and shared in the below link,
Kindly run the web service project first and then Angular. Also ensure to use both client and server side of same version.
Please try it with the latest version and revert us with more details and the modified sample, PDF document, replication procedure if you are still facing the issue. These details will be helpful for us to investigate further and assist you better.
Regards,
Akshaya