OnRectTransformDimensionsChange not called if Canvas NOT PixelPerfect?

I was working on a UI element that can be dragged around by other devs while not in play mode. Whenever the element is moved, some code needs to be called.

For this, I wanted to use the OnRectTransformDimensionsChange() method. As long as the canvas is pixelperfect this works fine! However, when the canvas isn't pixel perfect the function isn't called anymore!

I was looking around in the UI source, but the only reference I found where pixelperfect is used is in the graphic's...

OnRectTransformDimensionsChange not called if Canvas NOT PixelPerfect?