After upgrading Jenkins to version 1.483, I see this behaviour:

Changing some (other) values on the Jenkins settings page, the Maven installation entries get lost after the save.
This results in broken maven build jobs, because they are missing their configured Maven installation.

Trying to reconfigure a Maven installation on the Jenkins settings page has no effect. After calling "save", the Maven entries disappear.

I have no log to present, because I had to downgrade Jenkins to version 1.481 to get my builds working.