I just discovered strange thing.
I can reproduce it always.
How to reproduce.
with clean IDEA installation if you choose: Setting -> Editor -> Highlight current scope, you will see nice scope size "bars" showing up on left side of the editing panel. I love it.
Now, go to Setting -> Colors & Fonts -> Java -> Matched brace. Lets setup matched brace Foreground to something visible (red for a moment) but after that it is visible enough so Background I like to have same as everywhere (so uncheck Background). Apply.
Our scope bars disappeared. :(
I hope that I am just missing something.