Unable to click or easily click and drag lines

I haven’t played this game in a while, I’ve come back to it, and now I’m struggling to pull lines around. Early one, the first two lines are no problem, I start having issues with lines three and onward. I’m looking at my mouse pointer right on top of the line, but it won’t drag at all.

When I’ve got little symbols waiting to move, it’s very frustrating not being able to drag a line to attach it to a station symbol.

This is not an issue of not having bridges or tunnels to go over water, I can’t get it to latch and drag at all. It’s like I’m clicking nothing at all, dragging nothing at all, the line doesn’t respond to my mouse drag.