Can't Select Entities at Non-Zero Elevation

[Schumi]

We have a civil engineering file with contours (2D polylines at their real-world elevation). Twice now, for unknown reasons, the drawing gets to a point where we're unable to select any entities unless they are at 0 elevation.

I tried resetting the UCS, audited the file, etc. but nothing seems to help.

We are running a third-party civil package, so there may be something going on there, but I wanted to see if anyone had run into this or had any ideas?
Thanks,
TJ

[Strix]

let's move this out to 'bugs and quirks' and see if anybody can answer it there (esp as it's not an AutoCAD Civil product :wink: )