Fobus Roto Paddle Double Magazine Pouch P2000SK Retention Issue

Just purchased a Fobus 6900RP and it doesn't retain my P2000SK magazines at all. The really strange thing is that it works perfectly on my P30 mags which are completely interchangeable in my SK. I looked at the magazines and cannot see any difference, but when I put the SK mags in they fall right out. In fact it seems as though the pouch is pushing them out a bit. The P30 mags are happy in the pouch even while upside down. Has anyone else had this issue before? I am completely flummoxed as to the cause or how it is even physically possible. Here is a link to the item I purchased:

Amazon.com: Fobus Roto Paddle 6900RP Double Mag Pouch Glock 9& 40, H&K 9&40: Sports & Outdoors