We have tried all plugins off and default theme – it is showing up as an object on the screen but is not visible as if the color is white like the background
The loader color picker was somehow overwritten by another script. It’s still working but it looks like in some cases it selects a transparent color – which was causing the problem.
In case you experience the issue again, you can fix it by clicking on one of the pre-defined colors, and then creating your desired color again: http://i.imgur.com/21JLtRM.png