Today, one of my coworkers built a terrain element from corridor breaklines, but accidentally selected two breaklines that were not surface breaklines. All efforts to remove them from the terrain element failed. The elements would allow selection, and within the same command, the prompts would indicate the element was no longer part of the element. But as we finished the command, the terrain element would not update and if we hovered over the elements, they once again identified as part of the terrain element.
We finally had to delete the terrain element and rebuild a new one before we could get a correct terrain element.
I don't have a recollection of this occurring with removing elements from a terrain. Were you using the Terrain Model > Remove Features command? Did you try editing the terrain on another machine to see if it was specific to this user? You may also want to get the latest SS4 update installed (currently 08.11.09.878) from the Software Fulfillment Center to see if it will help with these type issues.
For more information about the Road and Site design tools, visit the Road and Site design WIKI at: http://communities.bentley.com/products/road___site_design/w/road_and_site_design__wiki
Here is a link to the process for removing features from a terrain. You may be using this process but I would like to include it for future references to this subject.
http://communities.bentley.com/products/road___site_design/w/road_and_site_design__wiki/26438.video-remove-features-from-terrain-model
Yes, this is 3 years old. Yes, this problem still bothers me periodically.
How do we remove a break line from a terrain model when that break line no longer exists because the corridor model no longer generates it?