John Jay, if you use the IMS you can check if there is any HN bad by the command TECF.
Regardless of the whether or not a fault with the HN ,you can make learning them - TECCR to clear them, than TECC to teach.
If the TECF command shows any HN faulty and it remain after doing their learning , try to replace their HN without forgetting TECCR and TECC after.
When a HN is faulty / not in network , the TAC50-04 sends the cars to the respective floor , precisely so that it will not be deprived of access to the car.
Concerning to Master or Slave Car, does not matter at all cause you can switch that condition between the cars any time you want it.
