ORD Measure Area anomaly

I'm using ORD 10.08.01.33. I quickly made two dummy DGN files to test some weird behavior that I was seeing on a project:

• a.dgn contains a half-dozen lines & arcs that create a shape (but they remain individual elements and are not a chain or closed shape). It also contains an associative region, drawn with a maximum gap of 0.001.
• b.dgn is a blank DGN that merely references a.dgn.

The shape & region are shown below:

If I'm in a.dgn, the area of the gray region is 17763.434 SF, measured using both the element properties and the Measure Area -> Element tool.

If I'm in b.dgn, the area of the gray region is also 17763.434 if the a.dgn reference is not clipped. If I draw a random fence safely outside the shape and Clip Boundary to the fence, the area (measured with the Measure Area tool) changes to 17601.550 SF!

No Clip: (17763 SF)

With Clipped Boundary: (17601 SF)

I tried to duplicate this behavior in PowerInRoads SS10 and could not. The area of the region was the same, regardless of whether the boundary of the reference was clipped.

Why does Clip Boundary affect the output of the Measure Area tool?

a.dgn     b.dgn