I feel your pain, but sadly do not have an answer other than to point you to the roon forums as tomcy6 has done.
And a reboot never hurts as mentioned above. 😉
There are often times when I am ready to give up on Roon. The problems are numerous with software updates seemingly on an every other day basis. The software feels like an early access computer game where you pay the developer to play a game that is still in development. You end up paying for their start-up costs.
I am running my own core on a reasonably powerful PC dedicated to the task with a fresh OS install. I've had it crash to a point where I had to delete a directory and let the core rebuild files it needs. I though I had the reference I used bookmarked but cannot find it just now. I think it was C:\Users\UserName\AppData\Local\Roon\Cache. But I am not sure at all and so please DO NOT delete that (or any other) directory unless you confirm with RoonLabs first.
Good luck.