Mine does this too intermittently. Someone started a thread about it a while ago and a few other people said they were experiencing it as well.

They probably told you the fluid was "dirty" so they didn't have to diagnose it any further in hopes maybe there would be some placebo effect or that you would just learn to live with it. Modern transmission fluid turns dark pretty quickly from normal use, so unless there was actually metal flakes in the fluid, im sure it was fine. Seems like more of a software issue causing the surging.

 

Thanks, Wrong Side of the Trax.

 

I'm having this issue as well. Seems more like a fuel injection/turbo/combustion chamber issue than transmission. I generally notice it when I'm on the highway at cruising speed (not accelerating) and then go up an incline. When the engine is under load it seems to buck/surge. I first noticed it with the adaptive cruise control on so thought it might be that. But now I sometimes notice it when I'm not using the cruise control. I haven't brought it in yet to the dealer. Waiting to see what others say. (2024 Trax - 6,500 miles)

 

The auto center drained transmission, flushed and refilled it on a 2016 Trax with 83000. Less than 50 miles of driving, the accelerator stopped working and car would not move. After returning it to the same auto center, they stated we need an entirely new transmission for approximately 7500 ... nearly the value of the vehicle itself. Would you recommend replacing the transmission on the Trax or scrapping the car completely?

 

Sounds like a software issue not a fluid issue.