[ubuntu_mate] Odd/Unexpected behavior with Alt+F#

I'm having some odd behavior with my newly installed Ubuntu 16.04. I would normally (on previous Ubuntu machines and other Linux distros) press Alt+F1 to open the main menu, Alt+F2 for a run dialog, Alt+F4 to close an application, etc., etc. However, I'm now greeted with a change to tty1, tty2, or tty4, respectively. Interestingly enough, Ctrl+Alt+F1 (and F2, F4, etc.) still switches to tty1 (and tty2, tty4, etc.) as well (which, in my opinion, this later keyboard command is the de facto standard). Not only this, but when I navigate back to my desktop after the "accidental" switch to tty# (Crtl+Alt+F7 --> tty7), I see the originally expected behavior---e.g., the menu is now open; or the run dialog opens; or the application that I wanted to close now closes. Is there a setting that I need to modify to change this (back) to the correct behavior?

I've checked keyboard shortcuts as well as keyboard layouts, but I'm not sure what setting is causing this.

Thanks for all assistance.
~~archery~~