WPMUDev Dashboard disapeared

This is not a huge issue. But it makes me scratching my head.

We have been working on this multisite and prepare to release soon. But I just found that WPMUDev Dashboard Menu on my Network menu is gone. The menu was there, and the WPMUDev Dashboard Plugin is still activated at the Network level. I am not sure what happened. Can you help me?

Darren