Cloudforms 2.0 Error when modifying smartproxy affinity

Issue

• When we try to adjust the smart proxy affinity for a second CFME appliance, an unexpected error is printed to screen.
• Steps performed:

Wrench, Configuration, select zone (e.g. default), click on "smart proxy affinity", select a different appliances -> error

• This only happens if there is more then one appliance in a zone.