Fusion360 DXF to Luban small dimension importing completley wrong

I am testing import DXF files from Fusion into Luban laser space, using up to date versions of both. I have quite complex files to import but am stumbling at the most simple dxf import.

Each files consist of centre rectangle sizes in mm of 10x10, 25x25,50x50, if i import to lightburn sizes import OK but I dont want to learn another program!

When I import a 10mm x 10mm cube or (25x25) into Luban it comes in as 30mmx30mm why is this?