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I insert a WBlock (another DWG on disk, drawn in BricsCAD) and it inserts in the XZ plane and I'm looking at the edge of it, one pixel thick. I have to 3DROTATE about the X-Axis to get it oriented correctly. The preview when I navigate to the file in the insert dialog looks right. What I can see on screen after insertion is a horizontal line that's actually the length of an X-axis projection of the block drawing. I thought maybe I unintentionally drew on XZ when creating the block, but checked both the block drawing and the host drawing and both are in XY.
If I insert an old block originally done in ACAD it works correctly.