DIAGNOSIS The printer's ink level monitoring, which is tied to the HP+ and Instant Ink system, has lost communication with HP's servers or has a corrupted local counter.
FIX First, check your internet connection—the printer needs to phone home to validate Instant Ink cartridge status. If online, restart the printer. If that doesn't sync, you need to reset the ink counters. Turn the printer on. Open the cartridge access door. Press and hold the (i) information button for about 5 seconds until the carriage moves. The printer will reset its ink level estimation.
IF THAT DIDN'T WORK You may need to re-register the cartridges. In the HP Smart app, go to your printer, then 'Instant Ink', and look for an option like 'Manage Plan' or 'Update Cartridge Information'. There's often a 'Sync' or 'Refresh' button. Follow the prompts.
HEADS UP This is a downside of the HP+ system on this model. If you use non-HP or refilled cartridges, the printer will likely lock you out from printing entirely. The 2855e with HP+ is designed to only work with HP-original chips that can communicate with the service.