macOS Sierra has a serious problem with PDF files that are edited using the Preview application, many users have reported this in recent days. According to people who encountered the problem, macOS 10.12.2 is mainly affected and trying to edit PDF files with the Preview application has the effect of corrupting the uploaded documents.
It does not happen in all cases that PDF files opened with the Preview application in macOS 10.12.2 are corrupted after saving, but the chances of this happening are very high. For now, no one knows exactly what problems exist with the Preview application since it corrupts PDF files, but it is speculated that the changes made by Apple in PDFKit for macOS are at the root of them.
It is not known yet if Apple is aware of this problem of macOS 10.12.2, but there are quite high chances that it knows about it and tries to solve it. In the meantime, if you have to edit PDF files in macOS 10.12.2, it would be better to use any other applications besides Preview and edit copies of the documents, not the original documents.
"It pains me to say this, speaking as the co-author of "Take Control of Preview," but I have to recommend that Sierra users avoid using Preview to edit PDF documents until Apple fixes these bugs. If editing a PDF in Preview in unavoidable, be sure to work only on a copy of the file and retain the original in case editing introduces corruption of any sort."
