Hello, I contacted CS about this last week, but didn't see it make it into the Known Issues. When I use training blessing, sometimes one of my Barracks will freeze and not produce any troops. Since I am usually doing other things while training troops, I frequently won't notice this for a few minutes, which results in a significant loss of time on my training blessing.
However, with the retrain button, this is apparently worse. While using the Training Blessing, and the retrain button, all three of my barracks froze while building troops. I didn't notice this for 2-3 minutes, and my training blessing ran out soon after I noticed. This added over 10 minutes to my training time (I had just enough time to finish all three barracks with the training blessing when I started it). This is a really frustrating bug, so I hope you can find a way to resolve it.
However, with the retrain button, this is apparently worse. While using the Training Blessing, and the retrain button, all three of my barracks froze while building troops. I didn't notice this for 2-3 minutes, and my training blessing ran out soon after I noticed. This added over 10 minutes to my training time (I had just enough time to finish all three barracks with the training blessing when I started it). This is a really frustrating bug, so I hope you can find a way to resolve it.