I am encountering the same problems with upower and the hardening-runtime packages in debian testing. To get things to seeming work again I had to comment out user.max_user_namespaces = 0 which is one of the sysctl parameters added by the hardening-runtime package.
Hope this helps narrow things down a bit as I would like to keep user_namespaces disabled on my laptop.-- Securely sent with Tutanota. Get your own encrypted, ad-free mailbox: https://tutanota.com
