Mag failure to feed

I have a brand new 64. The very first time I loaded the mag with 10 rounds it would not feed the first round into the chamber. I had to remove the mag and pry the top round back out. With 9 in the mag it would feed. Yesterday I was at the range and I loaded the mag with 9 and it would not chamber the first round. I ended up loading only 8 for the rest of the session. Is this possibly a bad mag? I did try it with 10 again and it didn't work. So I took one out, but still no good. Only seems to work with 8 in the mag.

Mine did it yesterday, out of the box too, but it only did it once, I shot 75 Rnds with it