Hello @richsmif ,
Welcome to the Poly Community.
Our Partner Microsoft has not validated UC Software 6.0.0 or 6.1.0 via their 3PIP program. This means these Software versions will not be able to sign in to Skype for Business Online.
A working firmware is 5.9.3 which is available and can be used.
Please ensure to provide some feedback if this reply has helped you so other users can profit from your experience.