I came across this frustrating behaviour. You can see I try to move the label, and see three different blue centre lines I can choose from.
It’s not clear which of the blue lines relates to which object on screen. I know I can select the two objects in the centre and use the alignment controls, but this is a case of switching contexts, which is even more frustrating when I’m quickly moving things around with the mouse.
Here’s an animated GIF showing the problem: