I noticed it's a UnityVS project. The debugger is not 100% trustworthy in that case... Maybe add some Debug.Log calls and double check that Unity is executing the latest version of that code?
Ok I guess. I've reported this error to the UnityVS team. I was told this is a possible race condition, where the variables are not refreshed/updated long enough while the debugger is attached to Unity running on different threads. Maybe it's a rare corner case scenario, who knows?