Diagnosis
The printer's ink level detection isn't reading the physical tank; it's estimating based on page count and cleaning cycles. The sensor for the INKvestment tanks can get dust or ink mist on it, or the estimation software just gets out of sync.
How to Fix It
Ignore the message and keep printing until you actually see print quality degrade (streaks, fading). The message is a warning, not a hard stop. You can usually press 'OK' or 'Stop/Exit' to bypass it and continue printing. The printer will let you run the tank much lower than the warning suggests.
If That Didn't Work
If the message is persistent and won't let you print, try resetting the ink level monitoring. Turn the printer off. Open the front cover and hold down the 'Go' (triangle) button while turning the printer on. Keep holding the button until all LEDs light up, then release. This can recalibrate the system.
Heads Up
Don't remove and re-seat the ink tanks unnecessarily trying to 'reset' it—this can introduce air into the lines and cause real printing problems. Only remove a tank when you're genuinely replacing it with a new one.