Ah, I've been using a Razer keyboard that is not yet supported for OS X... so I've been hacking my way around this by plugging it into a windows machine and then sharing the trackpad/keyboard with my Mac via Synergy server. I've only encountered one other issue so far with this setup so it escaped me that it might have been the culprit. In the other instance where this was causing a problem - there was a security prompt asking whether or not I wanted to accept an unidentified SSL handshake.
It was clearly recieving the click & return key inputs, but the console revealed that it was denying input from my shared keyboard/trackpad because it wasn't considered a trusted input source...
I don't know if this helps... but yes - when using shared input devices - clicking and dragging an object in the Workflow layout not only does not actually move the item... it also hides the mouse until I either open a context menu and left click outside of it, or activate Mission Control.
EDIT: With this realization in mind - I am not quite sure if this is a problem that JUST popped up as I've only had this setup for about a week or so.