But this one has me speechless, the editor's gremlins have triumphed.

This is AMTRACK map, I edited, had hollowed out the train, added better teepees/tents/wigwams and made a few small fixes and changes...
I rebuilt... then saw what u see...
There is no terrain in the 2D view, but u can see cleary in the 3D view, that a dirty great piece of grey terrain, not unlike Vandenberg terrain, has decided to arrive on the map, being even thoughtful enough to leave a road up to the hill...
how strange is that? Can't delete it cos it's not there in the 2D view.
Also you will notice that some "initial subtractions" are missing and the map at ground level has got smaller, burying the train outside the map. Only the subtracts from the train remain visible, outside the map...
A few things I just can not figure out.
My only guess is that because I used the bunker terrain brush from Area51 (the hilly ramp going down into the bunker), that somehow the terrain has gone wild...
I cant re-add the initial subtraction brushes, because they will just eat away anything already buried outside the map, will have to move everything off the map and put back the initial subtractions and then re-add what I can, and rebuild the rest...