Disappeared viewfinder in Open Brush

Hello. Everything worked well before. A month ago there were no problems. Yesterday I tried to run mixed reality with Open Brush using LIV via Steam, but after syncing and running Open Brush, the viewfinder disappears and I can't see myself from the outside. I use everything as before. I tried to connect through the camera of a smartphone and a laptop. Oculus Quest 2, link cable.