Inkscape can be successfully used with Design Space. This information can help.
Document Properties Settings:
The settings work well. If you need to change your scale, always select all (ctl-a), cut (ctl-x) then change the scale. Double check the settings, then paste in place (ctl-alt-v).
Look at your objects panel. If your objects are under a layer, select all the objects, and cut (ctl-x) Right click on the Layer in the object panel and choose delete. Then paste in place (ctl-alt-v) on your canvas to get the objects back.
UNgroup (shift-ctl-g) and REgroup (ctl-g) each group immediately before saving. (or don't use any groups if you can avoid it. It simplifies saving a lot.)
Save as "PLAIN SVG" (save will always revert to an Inkscape svg, so always "save as" and re-select the plain svg option. )