Starting several days ago, only the web browser client has been getting this issue. I have “Secure connections” disabled to improve playback performance, especially with Chromecast. From a browser already logged in, it prompts for me to choose a profile. If I choose the main profile with a PIN and enter the pin, it spins for a few seconds, then shakes and wants me to re-enter. If I choose another profile without a PIN, it thinks for a few seconds then does nothing. The problem is only when accessing from other systems. I’ve tried Chrome, Safari, and IE. Same problem. If I use a browser on the same system as my Windows Plex server (1.8.1.4139), I can access the web console just fine.