We received the reply from Octane team: they have simplified the standard render Max procedure for performance reasons, and therefore the RailClone objects are not updating their render state.
It can be fixed in the following way
Open the Render Setup dialog-> Kernel tab-> Render Settings rollup-> 'Notify objects on render' option can enable it for all objects / none / per object.
So 'All objects' or Per object' should be used. If Per object, select the RailClone objects, and open the Octane object properties, enable the 'Use Render mode' option.
Also in the Octane object properties dialog, 'Movable proxy' should be enabled too, to make sure changes (object parameters, time line, ..) will be updated to Octane.
Please note this change would affect the render performance.
I hope that helps.