Hi there,
I signed in to compositor, and granted access to my public repository then played a bit with compositor (https://github.com/mlcdf/compo). Then, I signed out and signed in again, it still worked. Finally, I revoked compositor's access to my GitHub repos and re-enabled it (but addrf access to organization repositories too). Since then, I get an "Could not get site" error when I try to edit one of my site or when I try to create a new one.