Let's look at the reason as to why the multi-copy feature may not be working as expected.
The multi-copy functionality within Lineardraft is one that can rapidly speed up the time it takes to design OCS. The way in which it removes the monotonous and iterative processes by creating multiple instances of structures, creating a 3D model, creating a 2D layout, producing cross sectional saved views, cascading wires & equipment along a track, plus much more really speaks volumes about the powerful nature of the feature.
But what if it doesn't work as you expect it to? Well let's take a look at the reason that might be.
The calculation and placement of multi-copied structures depends heavily on the quality of the referenced track alignment. If the line strings that represent the rails are 'broken' within the area that you wish to automate, then software will not be able to calculate, and subsequently will be unable to place the requested number of structures.
The software is intelligent enough to recognise when and where the line strings break, therefore the multi-copy will be performed up to that point.
To carry your structures on beyond this point, simply measure and plan the next structure manually (still using Lineardraft functions), connect the wires (if applicable) from the previous structure and then perform a new multi-copy from that point onward.