I would expect an application that uses a single midi port would automatically ignore the remaining ports on the system. This editor is third party, made by an individual, i believe. I have enjoyed using it, as it is a thousand times easier than using the two line LCD on a unit as complex as the DP4. Here is a link:
It seems if i open it last, it doesn’t steal any ports already in use, so that is certainly a workaround, but i would prefer to figure out what exactly is happening so I can rely on it.
I’m in the process of rebuilding the whole MIDI configuration now, testing at each step to try and break it.