I have the same persisting problem since a long time, only way to install is by the downloadable files or to switch to a different, freshly installed user account: then SDA works fine and I can install everything for all users.
I have the same persisting problem since a long time, only way to install is by the downloadable files or to switch to a different, freshly installed user account: then SDA works fine and I can install everything for all users.