SPARK-1361 a 5000 history messages limit was introduced to speed up History loading (all messages are still there, just not showing). But it shows not the last 5000, but the first ones. So you can't find last messages in your history. Should be reversed.
Currently one may control this by adding maximumHistory=xxx into spark.properties There should be an option in the Preferences to change that value. It can be 5000 by default. This option can be removed when history loading will be improved, but this doesn't look to happen very soon.