I’m currently working on a Forge app that uses Forge + Connect hybrid. The installation on my Confluence site works fine:
The app is visible in Manage apps → Installed apps.
The manifest includes several connectModules such as confluence:generalPages, confluence:spaceToolsTabs, confluence:contentBylineItems, confluence:webItems, etc.
However, after installing, none of these modules appear in the Confluence UI (not in the Apps menu, not in space settings, not in page byline, not in editor toolbar).