Cannot save setting vs. drop-down list property.

Description

Steps to reproduce:
Go to Admin > Config tab > Edit custom property Types
Edit "Drop-down list" property
Add Setting
Add Name and Value for an option (e.g. "option1", "value1")
Save

Actual result:
User gets message "Index was outside the bounds of the array.". The setting isn't saved.
Please see attachment for screenshot.

Expected result:
The setting should be saved corresponding to the selected "Drop-down list" property.