My Robo E4 Pro is printing but no filament is coming out.

First, make sure there is not a tangle or knot on the filament spool. If so, unload, detangle, and reload your spool.

If there is no tangle, make sure your temperature settings match the filament you are using. Different brands of filament and different types of filament have different requirements for extruder and build plate temperatures.

If both of those have been checked, your printer is likely calibrated too close to the build plate.
Cancel the print, clear off what has already started, and then go into Tools/Calibration. Run through both Z-Axis Calibration and then Sensor Calibration.

If this doesn't solve your issue, you may have a jam in your extruder. Refer to our article on unjamming your printer here.