When placing centered TeX into a blockquote, regardless of the theme used, it fails to render properly using Live Preview. This persists even with the stock theme and no community plugins active.
Please resubmit this bug report and make sure that: 1) you follow the bug report template, 2) you use the default theme (no css) and 3) there are no third-party plugins enabled (You ca n use the help vault for 2 and 3).