Actor Transformations help

[CainReval]

So ive been using Yanflys tips and trick videos to make some pretty cool effects for some of my characters. Up until now, all my effects have been changing characters to those of similar size. Recently with Aekashics updating their monster log, I wanted to use a slightly modified Tiamat as a transformation (By slightly modified, I simply mean changing the size so it is smaller and making them green to match with the character im using) The problem Im encountering is that anytime an animation plays over the image of the character in the transformed state, a black box appears behind whatever animation is playing.





Could it be because Im using an image that is larger than the base I have for my standard character? Or could it be another issue entirely?


Just for reference, these are the main character that is using the transformation and the transformation its self, respectively


Standard form


Transformed State