Not sure if this is a bug or intended behaviour. If it is intended behaviour, then I have no idea why it was designed this way...
My problem is that when I am dragging a pre-existing track on a PCB layout that has only two vertices, interactive routing rules are not obeyed. This means that you can drag the track anywhere, including on top of other tracks. If you reshape the existing line segment first (add more vertices), then subsequent dragging will obey interactive routing rules.
I'm running Circuitstudio Version 1.5.2 (Build 30)
Here is a video demonstrating the bug: