I have, on occasion here. I haven’t paid attention to specifics, but it’s when somebody posts a comment (in a thread full of comments) that contains a YouTube clip, and when I go to fullscreen the YouTube clip, it does what you describe. But only on occasion. Noticed it maybe three times in the past couple of months, thought it might be a YouTube issue (as in, doesn’t want to fullscreen when embedded in anything).
Chrome Version 53.0.2785.143 m on Win10
