IMO, the real problem is that the front of the mag is cut out too low. If you look at any other mag, the next round is always being dragged forward, it's just that it's stopped by the front wall of the mag...
In the meantime, I discovered another problem with the Wilson ETM -- It sits too high in my gun and pushes up the ejector. After a range session with this mag I couldn't pull the slide off as it was stuck on the ejector. Fortunately I was able to push the exposed part of it down enough to get the slide off... A quick search reveals that this is a known problem.
I don't want to modify my gun to fit a mag :/ I ordered the Metalform 10 rd mag from Brownells. Will try that next time. For the price, it should work