FS#2580 - Drawing Prefs > Page offset displayed with page units
Andrew,
Related topic: https://www.qcad.org/rsforum/viewtopic.php?f=89&t=10934
For the drawing included in the topic: Mobilhaus.dxf
Drawing units: meters
Page units: millimeters
Page areas are defined by the user in Model_Space with a lower left corner at:
(0.0,0.0) , (21.0,0.0) , (42.0,0.0) , (63.0,0.0) and (84.0,0.0)
This are drawing units and thus meters.
When we setup the printing region to print page 2:
Scale: 1:100
Offset X: 21 (mm)
Offset Y: 0 (mm)
Prints perfectly.
But 21m in scale 1:100 would be 21cm or 210mm and that is indeed the width of a page.
Other test have shown that the Viewport offset is in drawing units.
And not 21 (mm) as displayed in the Drawing Preferences .. Printing .. Page widget.
Probably not OS related.
Tested in 3.30.0 and 3.27.6 on a Win32bit
In the topic there is also a revision of the file using Layouts and Viewports.
The most applicable way to approach something like this 
Then the Viewports centers are also in drawing units.
Regards,
CVH