Command: New
Command: Line
Start of line ( BothSides Normal Angled Vertical FourPoint Bisector Perpendicular Tangent Extension ): 0
End of line ( BothSides ): 1
End of line ( BothSides )
1 open curve added to selection.
Command: Length
Length = 1.000 inch
Command: Distance
First point for distance ( Units=Model_Units )
Second point for distance ( Units=Model_Units Undo )
CPlane angles and deltas: xy = 38.608 elevation = 0.000 dx = 0.781 dy = 0.624 dz = 0.000
World angles and deltas: xy = 38.608 elevation = 0.000 dx = 0.781 dy = 0.624 dz = 0.000
Distance = 1.000 inch
Command: Distance
First point for distance ( Units=Model_Units )
Second point for distance ( Units=Model_Units Undo )
CPlane angles and deltas: xy = 38.608 elevation = 0.000 dx = 0.781 dy = 0.624 dz = 0.000
World angles and deltas: xy = 38.608 elevation = 0.000 dx = 0.781 dy = 0.624 dz = 0.000
Distance = 1.000 inch

I’m sure you know where you are snapping here (or not snapping?), I just tried snapping to the top and bottom and to the left and right of those naked edges

Successfully read file “E:\Tech Support\Disco files\Martin Siegrist - L.3dm”
Command: Distance
First point for distance ( Units=Model_Units )
Second point for distance ( Units=Model_Units Undo )
CPlane angles and deltas: xy = -90.000 elevation = 0.000 dx = 0.000 dy = -0.917 dz = 0.000
World angles and deltas: xy = -90.000 elevation = -90.000 dx = 0.000 dy = -0.000 dz = -0.917
Distance = 0.917 inches
Command: Distance
First point for distance ( Units=Model_Units )
Second point for distance ( Units=Model_Units Undo )
CPlane angles and deltas: xy = 180.000 elevation = 0.000 dx = -0.917 dy = 0.000 dz = 0.000
World angles and deltas: xy = -180.000 elevation = 0.000 dx = -0.917 dy = -0.000 dz = 0.000
Distance = 0.917 inches