I had some free time this morning, so for the hell of it, I decided to install the portable version of MC... MulticCommander_x64_Portable_(12.8.0.2929) into a separate folder... and surprise... all the buttons worked, but not the full installer version.
I compared all the settings in the full and portable and found one thing... under View - Toolbars... the portable had Standard checked and the full did not... I checked the Standard in the full and what do you know... all the buttons worked again