Definitely try the full memory reset. I had the "stuck key" behavior on mine (advantage pro) from where I didn't understand how to remove a macro, and had simply made a key a macro for itself (a = a). Sometimes if a key is macro for itself, it'll loop that way, and it'll definitely lag in registering when you press it.
Another thing, it seemed a bit funky sometimes with numlock off. I've always left numlock on, and not had any issues with the board whatsoever after resolving the macro confusion.
(btw, the correct way to remove a macro is to enter macro program mode, press the key or keys that triggered the macro, then simply exit macro mode without entering any other keystrokes, do NOT macro the key back onto itself lol)