Last modified: 2014-02-12 19:50:43 UTC
On a long-lived active topic or board, click History. There's a gap in which changes don't appear. This may be related to the range division (4 hours ago, "Last week", "February", etc.) It seems to be happening in master and 1.23wmf12.
Change 112833 had a related patch set uploaded by Spage: Fix history timespans logic https://gerrit.wikimedia.org/r/112833
Change 112833 merged by jenkins-bot: Fix history timespans logic https://gerrit.wikimedia.org/r/112833