Glith in 54 gnomes

I have a problem with the 54 gnomes in Plants vs zombies Garden Warfare 2.
I already picked up ALL 54 gnomes, not just one time, 3 times.
But the game still telling me I need one more to find... is one in the right shell next to the close door.
I also saw tutorials to find the missing gnome, so I know for sure I already find the 54 gnomes, but I think my game have a bug or a glitch. I see on internet that Im not the only one with this problem. So, please can help us with this.
My name tag in this game is: JBEASTIN69.