I have just upgraded from 3.3.0.10 to 3.3.0.11 (except that the Softaculous software installer said we were on 3.3.0.7). We use Bootstrap 3 theme.
The front page was white with black text. I have emptied caches and and tried to update Bootstrap plugin but I get a message saying I don’t have admin privileges or similar which is odd. I have reinstalled from a back up so the site works for now.
Have you checked your server error log and your browser console log for any error message? They usually have some insightful info regarding these issues.