Objects within a UI canvas stop updating after they've been disabled as a game object, even when re-enabled, and they also do not clear from being rendered. The only way to fix this after an object has been disabled is to interact with the parent Canvas object in some way.

Reproduction Steps:
1. Move the transform of "Button" around, and see it updates
2. Disable the game object, and observe that it's still visible
3. Enable the object and attempt to move it; the Rect will update but none of the graphics will
4. Select the parent "Canvas" and adjust it in any way, and notice that the "Button" will update appropriately

Reproducible in 2018.1.0a7.
Not reproducible in 2018.1.0a6.