Hi, I opened another thread on the mailing list regarding builds from new configurations lost in existing matrix job. Both problems look similar even though I did not loose any builds on disk and I did not need to restart Jenkins to loose the builds in Jenkins interface. Strange thing, upgrading from 1.487 to made some builds to reappear.
https://groups.google.com/forum/#!topic/jenkinsci-users/uBdlIp69uhQ Bertrand.