Installing Everest with Steam instance of Celeste

I have Olympus installed via the olympus package, (and also threw in (olympus.override { celesteWrapper = "steam-run"; }) the line after, though that didn’t change anything), and whenever I try to launch Celeste or Everest from Olympus I just get the popup: Everest is starting in the background. You can now close this window. I’ve tried turning off cloud sync in Steam, and ‘verifying’ the Celeste install multiple times, and that did nothing. I’m fairly certain it’s irrelevant, but just for ...