Bidirectional Signals and the Align tool (TS2019)

I'm using the RCAP SafeTran signals. They have a Post signal that provides an attachment for a second signal head on the "back side", forming a bidirectional signal. Supposedly, according to the TS Dev Docs on the Alignment Tool, the align tool in RW World Editor is provided for mounting signal heads to gantries etc... I figured it might work for this. So I get the second head "close" to the main signal post, near the attachment point. Then I follow the directions: click on the light, I see a line now, bring it over to the attach point and click there. THe only thing that happens is that the signal head flips around and points in the same direction as the one already on the mast. It doesn't move at all. I have tried CTRL+clicking, Shift+clicking, CtrlShift+clicking, clicking the head first, clicking the main signal mast first, lots of combinations. Nothing ever happens except the light flips around to "align" with the other signal. That would be OK if it also actually moved the signal head into place! What am I missing or doing wrong?