There are some circumstances where you can not save the annotation on the XPS Annotator, and sometimes the user has been assumed that the error is the XPS Annotator.

You can not save the annotations if:

• You open a read-only XPS files
• The folder that contain the XPS files is read-only folder

If you open a read-only file then we store the annotation beside the XPS files. And if the folder is read-only folder then we store the annotation in "My Document" > "XPS Annotator resources" folder.