I have the same gun, and yes, that 10th round is a bitch to squeeze into the mag. With some practice and lots of elbow grease, it goes in. When you load the mag with the slide locked back, the slide returns by itself more often than not.
The first time that happened to me at the range, I was a little shocked. After a while, I realized it happens about 1/2 the time..
Depending on how hard you push it up in there.. If released like that ALL the time, I wouldn't mind. But at random..?. Not what I expected.