Disappointed

Chelsie • Married: 04-12-2015. Due date: 06/28/16. Currently pursuing a Master`s degree in Secondary Education (6-12 grade).
So I went for my 20 week check up today and also to find out baby's gender. The doctor could not determine a gender because the baby's legs were crossed, was moving around too much, and the umbilical cord was between the legs. 
Has this happened to anyone else? 
This is my husband and my's first baby. We have a gender reveal party scheduled for next Saturday. We decided to go pay for a 3D ultrasound out of pocket for this weekend. Hopefully this gives us something we can reveal to family. 
However I am very thankful that baby was healthy and strong during today's checkup. 
Is it normal for babies to not cooperate during the ultrasound gender scan? Or is my baby just practicing being stubborn 😝