Dorico does not memorize mixer channel names

It is very strange but I am routing the channels with the NotePerformer Playback Engines and when I change the name of the channels in Dorico’s mixer some are memorized and others are lost when I open the project again?
What is the problem? What am I doing wrong?

We’ll need a bit more information to try and track this down. In theory, provided you save the Dorico project after you have changed the names of any of the outputs, those changes should be preserved.