Selection tolerances are much too tight when trying to select a line rather than a shape - you have to be within 1-2 pixels to select properly, which makes it super hard to select lines.

This can be fixed slightly by changing the UI scale, but only works if you change it to 'comically large'. It works fine on my MacBook so looks like a Windows problem.

Smart guides don't help since smart guides don't work when snap to grid is selected for some reason.

You can see the minute differences in the pointer position in the screenshots.