Hi @Tony_Withers,
I met with our development team to discuss this. It looks like there is an incompatibility with some of the new features we are using on Mac OS 10.9. The team is looking into options, but they also noted that we will likely need to be dropping support for this version in the near future to ensure that everything works properly as we have a very small number of Roon users on 10.9.
If you’re able to upgrade to at least Mac OS 10.10, that would be our recommendation to get this resolved quickly. Apologies for any inconvenience this may cause!