I've this issue for a while now, I'm using Premiere Pro CC Version 11.1.2 (22) build. It's the most up to date version as of today, I believe.
I'm colour grading my image, I have a set of LUTs installed in the creative folder in premiere. They work fine, it's only when flicking through the different LUTs when the bug appears. Using the left and right buttons on the preview window on the right, when you're in the default color workspace, when applying that preview it becomes all washed out, as if the LUT has had the blacks turned all the way up.
As you can see the preview window on the right is completely different the program monitor, and to undo this I have to cmd+z. I can't carry on and try a different LUT because it will keep this washed out look to all of them.