Ah, ok - I agree putting in the plan manually is an enjoyable thing to do sometimes.
I suspect that the ‘request ifr clearance’ to ATC once in the cockpit might not actually pick up the FMC’s stated cruise attitude. That could be a bug or missing feature, so worth a search here. I guess one workaround would be just to put origin/destination direct in the world planner, check/edit the cruise altitude for it, and then once in the cockpit set up the FMS with the actual departure/route/arrival info and request then? I don’t know if that would work, but might be worth a shot until it’s added or fixed.