I have had a similar problem, but I think I got it to work. When I create something in anvil, I often put a small rest at the very beginning, that way when I set the loop point I can choose the point right before the sound starts. I have had no looping problems when I did that, and it didn't require the doit method work around.
The only annoyance is that you have to manually listen to the whole track in soundbox and try and error till you find the perfect loop point.