If you are running windows 10 go into device manager and check that the USB hubs/ports are always powered. It is set to turn off after a period of time by default. I did this with my Razer Naga Epic and have had no issues since.
I've had the Razer mamba for a few months now, and it's generally pretty great. However, I keep running into the same issue.
Occasionally, the mouse stops working altogether, which forces me to disable and re-enable it (alternatively I unplug it). It doesn't lose power and doesn't occur after doing anything in specific. Any ideas?