Just returned from Epic 8-15 Jan 23. You are correct about being key card sensors to forward elevators for the the Haven, but they were not active on my cruise for guests. Only 1 elevator was used (manned by an Epic crew member) for Haven guests during port days, 1 to 2 hours in AM and 1 to 2 hours PM until final boarding time. The only key card sensor elevator used was in front of the buffet area port side elevator deck 15 for access to deck 16 and deck 18, both Haven areas. The elevator on starboard side deck 15, buffet area no sensors. This cruise was at capacity and according to one crew member the 2 previous cruises were full also. Made it a very long wait for elevators most times. Yes I did try using may card on the sensors and always got a red flash except the deck 15 to16 to 18 Haven elevator.