I try in good faith to read between your lines: Are you saying that the Core is operating to spec? Where does it say user code stops and never runs again should the Cloud disappear?
I thought the problem had already been well described and understood and that Spark HQ acknowledged it and said firstly it was an unavoidable issue and later said it could be fixed but not by them, sorry.
Bug report (and not a new one): It matters not one iota which of the three modes you are in. If you are connected to the Cloud and then (for example) you disconnect your router from the WAN, thus disconnecting the Core from the Cloud, the Core stops running user code.