Guillotine exports wrong dimensions for non-pixel documents

Summary:

After slicing an imported image according to guides, the exported slices are wrong.

See attached video for more info.

Version Info:

Inkscape Version: 1.0 (4035a4fb49, 2020-05-01)
Operating System: Manjaro Linux 
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.70.0
Qt Version: 5.15.0
Kernel Version: 5.7.0-3-MANJARO
OS Type: 64-bit

drawing.svg

simplescreenrecorder-2020-07-10_18.25.29

Edited by Nathan Lee