Just after upgrade from Kubuntu 13.04 to 13.10, Muon updater crashed when starting, After some restarts of the PC, it does start but without a menu bar. In the lower left corner, a dropdown list "More..." is visible which upon clicking shows some commands including "Check for updates Ctrl+R". However, neither clicking this option nor using the Ctrl+R keys has any result.
It's a duplicate of many bugs. More of a rant than a bug report... *** This bug has been marked as a duplicate of bug 326169 ***
Actually, it is _not_ a duplicate of bug 326169. That was about feedback when checking for updates. I maintain that the updater does not check for updates at all after pressing Ctrl+R or after pressing the corresponding command from the menu.
We fixed refreshing of the cache in one of the 2.1.x releases.