The crystal and dish won't spawn if one person in the lobby has already completed it. The spool and antenna will still spawn, because they can be used for both Richtofen or Maxis. You have to go to custom games ORIGINAL, and the people that do have the EE need to join in after the game has begun. Make sure it is original, I had a group the other day, we were trying Tranzit for 2 hours and couldn't realize why the NAV card table parts wouldn't spawn in, the guy had it on Easy, took us that long to figure it out, lol.
Same goes for Tranzit and Die Rise, if you've already completed it, you have to join AFTER the match has started. You'll be in spectator mode for round one so the people playing will need to kill all zombies to spawn in the rest of the team.