Late upshift from 1st to 2nd gear in the morning when engine is cold, but if engine warmed up for 3 or more minutes before driving, no late upshift, runs normal, even after fluid had been replaced.
My car has 128500 miles.
My car has an automatic transmission.
Many newer automatic transmissions have temperature-sensors in them that, on a stone-cold start, restrict normal shift to only the lower (or non-overdrive gears) until the engine coolant and transmission fluid reach a certain level which in many engines, is around 140 degrees. At that point, engineers generally consider an engine or transmission fully warm for fluid-circulation and engine-stress purposes (this is usually at the lower end of the normal range on an analog temperature-gauge, or when the blue cold-engine light goes off). In some cases, this temperature sensor may fail resulting in delayed shifting or erratic shifting. I would suggest having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.