I had two different loaners. First newer one would authenticate no problem. Second would not authenticate and I had to use my Electrify America account to charge. I was told that most of those loaners are buy backs from previous customers. Depending on the customer reservation it is possible that the free charging already expired on some of these loaners. Another problem is that you don't have an access to the lucid add with a loaner, so you can't authenticate through there. Apparently that functionality is coming in the future.
