Unfortunately Knife may be getting a little old
The 3D Tools macro was written by Bill D'Amico quite a while ago now and I believe it has never been updated (and that unfortunately Bill has no interest in updating it).
3D Tools is written using the Classic version of DCAL which is still mostly
compatible with the recent versions of DataCAD. One thing that I know will cause classic macros to crash is if they encounter polygons or slabs with more than 40 sides. Classic DCAL only supports polygons/slabs with up to 36 sides (entities with 37 to 39 sides will not be processed correctly, but it only seems to crash on 40+ sides).
It would be worth checking if the 3D Knife crashes you are experiencing could be caused by large polygons/slabs. If so I think the only solution currently would be for you to split those large polygons/slabs into smaller ones.