This is most likely because the computer is not providing enough power to the keyboard.
1. We have a very large battery inside the keyboard at 4000 mAh. It can withstand a maximum charging current of 2A.
2. When the battery is almost out of energy, the keyboard has to take in a charging current of over 2A from the computer's charging port. (2A for charging the battery, and 400 mA for the keyboard working normally.)
3. But a typical computer's USB port doesn't allow this kind of charging speed. The computer will view it as strange because keyboards don't often need more than 2A power from their port and as a result, it shuts down their port.
So the solution for this is：
(1) Disable your computer's port limitation. Please note that the solution may vary because it depends on your computer’s settings.
(2) Please charge it with a wall charger.
(3) Use a higher version of USB ports like USB 3.0 or USB 3.1.
(4) We might have to limit the charging speed in the future.