Comment 33 for bug 1643383

I just realized something. There is a possibility that these conversion factors are actually coming from the inx file which was also changed at some point. Here is the inx file that I am using, latest version. It contains conversion factors such as
    <_item value="25.4/96">mm</_item>
    <_item value="2.54/96">cm</_item>
    <_item value=".0254/96">m</_item>
    <_item value="1./96">in</_item>
which are based on 96 dpi instead of the old 90 dpi. Give this a try and see if it helps. The most recent version is also available at:
https://gitlab.com/inkscape/inkscape/tree/master/share/extensions