From a fresh install from the Mageia-7-beta1-x86_64 ISO, selecting the Cinnamon DE. On graphical login a pop-up dialogue reports
Failed to load session "cinnamon"
with the only option being to log out. In .xsession-errors there is the message:
cinnamon-session: WARNING: t+0.01587s: Unable to find required component 'cinnamon-screensaver'
Installing the cinnamon-screensaver packages fixes the problem. So it seems there is a missing requires in the cinnamon package.
Assigning to the registered maintainer.