I have a Document Library with many properties on it's Content Type.

After uploading many types of files and enteringtheir metadata (properties), some users may need to re-upload that file in the future. To do this, they are opening the Library in Explorer view and dragging the updated document in. After being prompted to Replace the file, they click yes.

In most cases, the metadata is preserved (jpeg, pdf, txt) but when Office documents are uploaded (xlsx, docx), all the properties are cleared when replaced.

What what might cause this? Is there any way I can have Sharepoint save the properties for a document when it is replaced no matter what the file type?