Groups disappear in classification UI

Steps to reproduce:

• deploy OpenNMS instance
• navigate to "Manage Flow Classification", open "Settings" tab
  > try to move the user-defined group down - this will not work, but anyway <
• hit one of the on/off switches in the "Enabled" column
• now, the page reloads and the groups disappear

If you navigate to another tab and back to the "Settings" tab the groups appear again. This problem ONLY happens when you try to move the group around. Otherwise it works as expected and you can hit the on/off switch without any problem.