Moving the motor to certain initial position
If you are using the mode "turn by N degrees", it will become stuck. However, you can try using the other mode - "turn for N seconds" and it will work. It will work because the first mode will keep trying to run the motor until the motor turns exactly by 90 degrees, and so the program will appear stuck. In the second mode the motor will be on for specified number of seconds and then the program will go to the next block even if the rotation was less than 90 degrees.