The Linear 1S Generator has the Limits - Material ID Equal to 1 enabled, because this is later used by the Conditional Operator to decide if open or randomized seats (0=Open / 1=Randomize) will be placed. As your spline is actually the Material ID 80 assigned, it doesn't place any seat. There is an easy fix - set all parts of your spline to Material ID 1.
Optionally, as the Selector Operator was introduced, feel free to "upgrade" that style as shown on attached screen-shot.
You can place the Selector Operator and wire the Randomize Operator in the first slot and the "closed seat" Segment into second slot. By exporting the Index parameter this can handle if "open" or "randomized" option will be used. This way the Linear 1S Generator isn't needed and can be disabled and used with any Material ID.
Hope that helps.