Don't reinstall Hermes because a plugin won't install. Update it.
Since November 9 the live Hermes plugin list has grown past the 2 MB the app accepts, so installs silently fall back to the old list the installed version shipped with — no error is shown. The fix shipped in v0.23.1: run hermes update, then install the plugin again. A useful reminder that a silent failure is worse than a loud one.