I updated to the beta last night, everything worked great until the morning, update was pushed, then I could no longer connect to the update server. Loading screen before the logging was stuck at about a quarter completed. Only was to fix was opting out of the beta
Having a similar issue myself where I click the "connect with RuneScape account" button in the beta app and it does nothing. Only way to fix it is to leave the beta program and uninstall that app. Wish the mods would atleast reply to these messages to say there seen them.