I animated a text bubble to pop up and I have text on it used "preserve underlying transparency" on the text. Although, when the buble is animating open, you can see the text leaking out of the edges slightly. I thought it could be beacause I have a drop shadow and motion blur but it isn't! thanks for your time!
Impossible to know. You need to provide screenshots of the actual appearance, timeline and effects as opposed to describing invisible elephants. Chances are you are simply not understanding compositing order and thus messing up things. A different workflow may be required, but without any understanding of your project structure we can't advise.