Also, yesterday the Service ABS and Service Traction Control and Service Stabilitrak lights all came on a the same time. Does that shed any light on the possible diagnosis?
To me, these new symptoms all but confirm it's one of the front ABS speed sensor harnesses.
The grinding noise is the traction control firing, which applies the brakes, and that is probably what makes it feel like the transmission is slipping.
The bad sensor connection makes the computer think there's a wheel spinning so it applies the brakes, which also makes the grinding sound.
Having the steering wheel turned stretches the harness which exacerbates the bad connection, so that's why you feel it more going left.
You still need to confirm which harness it is, but that's not too difficult. On both front hubs, you'll need to pull the wires out of the loom and inspect the last few feet of each one looking for a broken spot, or a flimsy spot where the wire is broken inside the still-intact insulation.