This continues to be a problem. Yesterday it happened at least 10 times, and it's happened three times this evening.
Don't have a clue what's causing it.
With the exception of once, at least one item turns blue (RS monochrome) and I get the error 'Save Project Error' and it can't save the project.
Best I can tell, everything that supports RS turns blue, and everything else keeps it's normal colors.
So far the work around is to select something blue, bring up RS, click around on a few styles, even though the object doesn't change styles, then click 'undo'. If everything changes back to the default style/colors, I can normally save the project.
Again, clicking on different styles does not change the style. No matter how many times I click on the styles, I only need to click undo once.
In most of the projects this has happened in, I'm not using/changing the Render Styles at all, either directly or from the composer.