I saw this once.
The shop didn't find anything and they brought it to me.
The rack was loose.
Just "tight" enough to hold it in place, but it shifted when turning left or right.
When the shop got it, they put it in the air and didn't find anything because there was no load on the wheels.

When I got it, I just lifted it enough to see under and have someone turn the wheel back and forth.
I could see the rack shift in the cradle.

A few turns with a ratchet and it worked like normal.