1. On a new sketch, or in an edit of a sketch, the yellow orthogonal inference lines do not appear on the first click to create the first line and disappear after about 500 milliseconds seconds after the click that ends the line and completes it. All follow on lines from the end of the first also lose the inference lines that appear at their end click 500 ms after the end click. Automatic relations are almost impossible. After there is one closed rectangle in the sketch, the inference lines for new line elements behave more normally but there is still no square inference shown to help close a rectangle. Lines at any angle behave the same. The rectangle that normalizes inference line display can be at any angle.
2. On a 4K or 5K screen, when a sketch element creation tool is active, the selection zones for sketch elements have scaled smaller in the same proportion as the sketch relation icons, tiny, and so it is very difficult to select points, lines and curves because the selection target zone is no wider than the displayed screen element. Just the position error in a good mouse is enough to cause frequent misses.
SW 2016 SP5
Windows 7 x64 SP1, all updates
nVidia Quadro M4000, Driver 375.63 (ODE)