Question

I restarted my game about 10 times trying to get one

Answer 1

It's possible, it just a very low chance.

The chances for a Lucario's gender to go to either female or male are...

87.5% of the time - Male
12.5% of the time - Female

Comments

Also note that a pokemon's  gender is determined when you receive the egg, not when you go to hatch it.