Just found the solution: Policykit Authentication Agent should be started manually under LXSessionconfiguration - Autostart .
Obviously this is not switched on in these latest beta versions upon installation. Now both Lubuntu Software center as well as Synaptic are OK on my PC.
Just found the solution: Policykit Authentication Agent should be started manually under LXSessionconfig uration - Autostart .
Obviously this is not switched on in these latest beta versions upon installation. Now both Lubuntu Software center as well as Synaptic are OK on my PC.