Hi Gracey,
Thank you for contacting Syncfusion support.
We were unable to reproduce the issue with the provided details. We have shared the sample in which we have tried to reproduce the issue in the below link,
Note: Kindly run the web service project first and provide that URL to the serviceUrl.
Please try it and if you still have concerns, revert us with the modified sample with replication procedure, list of annotations you were using, Essential Studio Version. Also confirm us whether you are opening the downloaded document in Syncfusion PDF Viewer or any other Viewers. These details will be helpful for us to investigate further and assist you better.
Regards,
Akshaya