On the stage "The Bridge", I have a harpoon trap on the rightmost space of the lower moving platform. It's been upgraded once. When I hold ctrl and hover over it, it says "right click to copy this tower". However, when I actually right-click, the upgrade screen pops up. The tower is not copied.

I repro on all other harpoon traps on the moving platforms. I also cannot paste settings onto those traps.