We apologize for the instability of composr.app and appreciate your patience. We are working on the statistics addon and trying to find an optimal way to store and render data. Unfortunately, we have yet to find a solution that can handle the traffic (and therefore, tens of millions of statistical records) of composr.app. We're working hard on one.
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#2327 - Composr 10b4: Subdomain zone mapping for adminzone results in blank pages
I did have to configure the cookie domain, but that's it.
The next beta has a big optimisation for menu blocks, which I have deployed for you. This solves the problem.