Multiple reports at enwiki and OTRS.

• https://en.wikipedia.org/wiki/Wikipedia:Help_desk#Why_No_Text_In_Article.3F
• https://en.wikipedia.org/w/index.php?diff=732245583&oldid=732245280#Unregistered_users_see_old_revisions
• https://en.wikipedia.org/w/index.php?diff=732245583&oldid=732245280#Why_is_this_article_showing_an_old_version_when_I.27m_logged_out.3F

I checked some random pages on RC while logged out and it's sometimes showing revisions which are outdated by several revisions. For example: https://en.wikipedia.org/wiki/List_of_equestrian_statues has three edits so far today but the last modified at the footer shows 29 June 2016, at 18:20 currently. Manual purging seems to fix these. I don't think this is a frequent occurrence so this is probably worth further investigation as it may be related to a recent change.