First off, I want to say that I have little to no idea what I'm doing. This is the second time I've ever tried to rig something, and the first consisted of only two or three bones, so this is my first attempt at a full body rig. That said, I could have made a mistake in the beginning of the rigging process, so the error may just be my sloppy rigging. I hope I'm not thaaat bad and this just happens to be a simple, common, and easily fixable error. Still after searching a while, I haven't found a solution, so I decided to ask here.
If I did this right, above is a picture of the model I am trying to rig. I've completed the model and skeleton, but only the body and head are connected to bones. I think I should note that this isn't the first problem I've had with the rigging, so I have already done a bunch of things, adding weights and normalizing in weight paint mode, although I can't say I'm sure I did those right.
Now this is the bug. As you can probably see, whenever the I rotate a bone on the X and Y axes, any objects connected to the bones rotated appear to shrink. The effect increases the farther the bone is from the starting place or a full 180°. Oddly the closer the bone gets to a full 180° flip, the less it distorts, so the effect is only noticeable between 0° and 180° rotation.
And, above we have the an example of the bug with the same bones rotated along the X axis. I'm fairly certain that this is even more distorted then when I rotated these bones on the Y axis.
And here you can see the distortion's effect on the whole mesh. So yeah, that's the problem. If anyone has a solution or a similar experience, please let me know.
And here's the blender file if anyone wants to see the error first-hand.