How to avoid regenerating previews for linked images?

This question applies to LIbre Office 7.1.4 for Windows and MacOs.

My home server hosts my Libre Office Writer documents and my images and the clients (Windows and MacOS) connect to it via WLAN, which is a bit slow of course. Therefore I have linked all images in order to keep the documents themselves small enough to read from and write to the home server.

However, this has only worked for the MacOS clients - they can open the documents and the preview images are loaded very quickly - apparently they are embedded in the document, which is exactly what I was after.

On the other hand, the Windows clients take forever when opening the documents, as they apparently are trying to regenerate the preview images every time the document is opened. At least that is what it looks like, because the image boxes are “empty” at first and only after a couple of minutes(!) the preview images appear. It appears to me that the large files are read in from the server every time the document is opened. This is even when the document is saved locally, the links are still pointing to the hi-res images on the server and for some reason they appear to be read in every time the document is opened.

Hence my question: is there any way to have the Windows version of Libre Office just read in the embedded preview images and not go out to the server every time the document is opened?

As an addendum, I measured the network speed of the Windows client at 40-50 Mbps reading and writing, whereas the MacOS client has similar reading speed, but only half the writing speed. Therefore I conclude that it cannot have to do with network speed that the MacOS clients are much faster opening documents with linked images. I suspect something very fishy is going on with the Windows clients.

Also, the size of the documents is very small, so I am pretty sure the previews aren’t embedded. Perhaps the previews are cached on the local machines and the MacOS cache works correctly, whereas there is a problem with the cache on my Windows clients?