I run up against this regularly. I’m in print mode and want to double check or update some information (that is not necessarily displayed on the score; I’m just editing metadata) and I always forget that I cannot access the info panel via cmd+I in this mode.
Did we ever determine why this is? I’m guessing it is to avoid Dorico having to re-render a score if, for instance, you added a lyricist in the info panel and the master page included that token.
In my case, sometimes I print a project, and then return to Dorico later to add other data into the “other” field, such as links to source documents, etc. in case I need to find them again.