I had noticed this on Stephenson-Siemens already and until now it was fine on Bridgewater, but now it seems to appear on Bridgewater either.
Clicking the "open line triangle" in stops details does not always work. Repeatedly Spamming mouse clicks on or around that triangle does eventually open the line in the line manager.
How to reproduce?
1. Take either Bridgewater or Stephenson as a starting point.
2. Open any stop that your currently selected company serves.
3. open the "Details".
4. In the "Lines serving this stop" list, click any of those triangles that should open the Line Management window with that line selected.
5. Notice it won't do so, otherwise step back 4. or 2. and try again.
6. Spam mouse clicks on that triangle, you don't have to move the mouse pointer at all, just spam clicks.
7. Eventually the Line Management window will open
I have no idea how reliable this reproduction case is, as this bug does not occour to new games. A few days ago (I guess actually yesterday) it was all right on Bridgewater.
I hope you can reproduce it with these steps.
I tried that and not only the line window - neither of connected industries or connected stops work. I could not open the line window even after many clicks.
Similar problem is with stops in shcedule window. Click on the arrow does not work, but a click just left of the arrow works