If any of the annotations you added to your PDF document in DocHub are missing or not displaying correctly while viewing the PDF in a different PDF viewer, please first try re-uploading your edited document to DocHub to see if those annotations appear as they should there. In most cases where this happens, the edits are included in the file but maybe a particular PDF viewer does not handle and display the annotations the same as DocHub. If they do appear correctly while viewing the edited file in DocHub, please submit a support ticket and let us know which other application you were using to view your document and which edits you made that were missing or displayed differently in the viewer you used.
Comments are going to be the main type of annotations that may not display in all viewers due to the fact that they are a unique type of annotation that uses pop-up windows that is not usual for PDF documents, but we'd still like to get feedback reports of which PDF viewers are not displaying them and how the comments appear or don't appear (for example, whether the sticky note icon shows up or not).
If you are trying to view your edited PDF while in Google Drive, we recommend that you open with Google Drive Preview (previously called Viewer) instead of Google Docs (docs.google.com) to ensure that all of your edits display as they should.