I haven't used that investment, but this can happen with other investments also. I would check to ensure you are following the investment directions precisely for mixing times, mixing speed, and setting time. I would also check that your vacuum mixer is drawing proper vacuum; as they age or get dirty they will draw less vacuum and this will weaken the investment. Lastly, are you using a printed or milled pattern the has a high resin content? This can expand quickly in a hot burnout and cause cracks in the mold that can exacerbate other issues.
