Problem: Flags and barriers don't move with the feature on an undo or redo.
If a relocation or reshaping of a network feature is undone or redone, the flags and barriers placed on it don't move with the feature.
Flags and barriers don't track changes made to the network due to an undo or redo operation. When an undo or redo operation occurs, the flags and barriers are still drawn at the position prior to the undo or redo operation. However, the flags and barriers are still associated to the features on which they were placed.
Solution or Workaround
Clear flags and/or barriers and re-place them on the moved features.
For those using VBA to customize ArcMap, instead of clearing the flags and/or barriers, just manually update the IFlagDisplay::Geometry property on the affected FlagDisplay object and refresh the ActiveView's foreground layer.