How do you know all of your glow plugs are working correctly? The start up conditions suggest they may not be 100%.
I’d verify each has the proper resistance and verify voltage during activation. I’ve seen a number of times where the wires will verify battery voltage without load but not be able to carry the necessary current to activate the GP properly. A voltage drop test can help pinpoint any weak termination points.
2012 JD855D OPS Black Poly Roof, Deluxe Cargo Box, Front and Rear Protection, Power Lift, Front Hood Rack, Rear Screen (homemade), 800 Watt Inverter, 2500lb Winch installed in cargo bed, Front and Rear LED auxiliary lighting (4" square 27 watt), Front and Rear CV Guards, Koplin Side Mirrors