Hello!
Same Problem. Cannot save any changes while trying to create a new job.
Same issue on three different MU Setups on different servers.
All running
Wordpress 3.8
BackWPup Free 3.1.1
PHP: 5.4
Tried reinstall of plugin and use of plugin in fresh MU setup without ANY other plugins.
I hope this gets fixed soon, as I want my Backups running again and after using you plugin for years I will wait a bit before looking for something else.