This isn't ge:s bug exactly, it is just mapper specific. Unless you provide the exact spot of where it happened (since it has to do with how many vertices are visible on the screen), this cannot be fixed by the mappers at all. This can happen in all source mods due to engine limits. It happened in Dragonball: Source too when I used to map since you were able to view large amounts of the map at one time (rendering many vertices). Give us a screenshot, and Inverted will see what he can do. If you don't, it won't get fixed.