Smart things not allowing me to add wind free A/C

I have tried multiple times but I am unable to add the last two A/C units to smart things. One is closest to the router so I know it’s not that. They set up properly the first time and now when I try and set them up, I have to deregister them. That works fine but right on the last screen where I assign them to a room, it just “hangs” then gives the following error message. I have successfully set up 3 but these last two are impossible. Any suggestions appreciated.