I’ll give it a shot. But I did resize them to have the same width and height. The problem I think is that it must also have an exact center. Dont know why, but ignition seems to calculate the center incorrectly. For example, ill drag an image from symbol factory and manually set the width, height, location, to whole numbers, with the width and height equal. As soon as the angle is changed, the coordinates, width and height all change by fractions. Over time, these fractions grow and the image begins to move.
This is the same issue as in this topic.
The last post has the solution that the OP used, but it’s a bit of a doozy.
Someone did suggest that checking “maintain aspect ratio” helped, but others said they still had the issue with it on. 
I know I’ll be beat up, but use a GIF and be done with it. 
Sounds like you have your problem solved! Since I’m using Perspective it may not be apples to apples but…
I have been using .svg files for my animated icons in Perspective at least the nice thing about them is that I can create the multiple objects, states if you will, all in one .svg file and then make them visible, change their color, move them with respect to one another, etc. by attaching tags to the various properties in the .svg file. I’m finding that I can “group” all of the animated objects when I’m creating the .svg and then they are all in a neat group inside Perspective as well.
Just food for thought.