MS-Office zero byte files / x-ms-cookieuri-requested

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I was wondering if someknown also suffers from ms office transfering zero byte files via webdav to a server.
It is hard to find good information on this topic, and I hope that here is somebody who knows about this.

My prblem is, that ms office sometimes sends file save requests without content, but with a header x-ms-cookieuri-requested set to true ("t").
My guess is that office does some sort of preflight request. But what should it receive?
Do I need to respond with a location-header set? Or does it expect a certin body or http status code?

I know that this repository is not maintained anymore (at least it seems so), and I'm not using this software.
But as I mentioned, I hopde that there is somebody with this kind of knowledge.