Diagnosis
That grinding is likely the lift column's internal screw or gear binding. It's often caused by the desk frame being slightly out of square, putting uneven pressure on one leg.
How to Fix It
First, lower the desk all the way. Get under it and check that all the bolts connecting the two side frames to the desktop are tight—especially the ones in the middle. If those are loose, the frame can twist. Next, with the desk empty, raise it all the way up and listen. If the noise is gone, the twist was caused by weight distribution. If it persists, you need to slightly loosen (don't remove) the bolts that connect the noisy leg's column to the side frame, raise and lower the desk once, then re-tighten them with the desk on a flat floor. This lets the column re-seat itself.
If That Didn't Work
Persistent grinding from one column only, especially if the desk also wobbles or struggles, points to a potential defect in that specific lift column's motor or gearbox. You'd need to contact Autonomous support with a video of the noise.
Heads Up
Never force the desk to move if it's grinding severely or stops entirely. You can damage the motor. The reset procedure from the first problem can sometimes clear a motor error that causes binding.