Problem: After re-opening a project Cubase seems to have forgotten the connections to the ReWire slave (e.g. Reason, Live etc.). The according MIDI channels are "Not Connected".

Cause: The Cubase project has been saved after the ReWire slave (or its project) has been closed. In this case the connections to the ReWire slave indeed didn't exist when saving the project. Thus Cubase stored the project correctly with "Not Connected" MIDI output routings.

This means one should not save a Cubase project after closing the ReWire slave or project. Or vice versa speaking: A Cubase project within a ReWire session should only be saved when the connections to the ReWire slave are actually existing.

Background: Users often are tempted to save ReWire projects with non-existent connections due to the following reason:

When you've finished a ReWire session you usually save both projects, the Cubase project and the project of the ReWire slave. Then you'll close the ReWire slave in order to be able to quit the ReWire host resp. Cubase. This makes the connections switch to "Not Connected" and induces Cubase to ask if you want to save this change when you close the project or Cubase. Since Cubase is too lazy to think it will even ask if you've saved the project some seconds ago and didn't change anything apart from closing the ReWire host.