"Compatibility" is a term applied broadly. If it works with some things, but not other things, it should not be considered compatible. I have Ableton Live as well, and Live has never failed to see MIDI from the keyboard. So I'm seeing the same as you, works just fine with Live, it seems. I've never recorded MIDI but the indicator lights up when I press a key on the keyboard.
The issue appears to be between Cubase and Arturia's keyboard. The plugins work fine if the MIDI has already been recorded. I have the Dr. Bob Collection as well, and all Arturia software works in standalone and VST form.
But the keyboard works only intermittently. Sometimes even the MMC won't see the keyboard and I have to cycle the power to get it to work.
Tech support wrote me again last night and recanted their previous statement. At least, I think they did. They seem to be writing their responses in French (I assume) and running it through Google Translate or something so the responses sometimes sound a bit odd. So at this time I cannot confirm whether or not Arturia states that their keyboard/software combo is compatible with Win7 64-bit or not.
As an exercise in frustration, I'm going to wipe my computer and start over with a fresh install and just install Cubase and Arturia and see if things work. I won't discount the possibility of a negative interaction between The Factory and other VST plugins.
Aftertouch seems to work somewhat intermittently as well, so I may be taking this one back, unfortunately.