Canvas / UI: Image elements turn dark

As the title explains, in Unity 5.5.0p1, my UI / Canvas Image elements have decided to malfunction and all of a sudden turn really dark. This issue started about 10 minutes ago as I type this. Out of the blue, on one playtest of a script, the UI turned self-aware

The colour is set to as White as I can, Material on UI Image sprites is set to None, everything is in order as it should be set normally. I toggle the lights, I change the ambient colour, nothing works. The Skybox disappears, my 3D cursors all of a sud den are lit all crazy, and there doesn't seem to be anything I can do to restore it to normal. Even my Title Screen got dark as s***.

Here's a screenshot. The "new" colours vs what the title logo is supposed to look like colour-wise.

 

Try changing the alpha value of the image, it darkens and brightens colour.