BAT60A diode allows reverse voltage
Starting at the bottom with the 1.5 volts being developed across the 3k3 resistor when fed 5 volts via a reverse connected BAT60A. Look at the data sheet: -



The reverse current might be (say) 0.5 mA and, that current forced into a 3k3 resistor produces a volt drop of 1.65 volts. Just throwing numbers together.

Prior to that you did an open circuit test of a reverse biased BAT60A and you saw the same voltage at the output and input. Should this surprise you given that schottky diodes have high leakage current and your meter might have an input impedance of 10 Mohm?


  Doesn't the diodes block the voltage?


They don't block reverse current or voltage anywhere near as well as regular silicon diodes but, regular silicon diodes have a larger forward volt drop.