I'm in the process of dealing with what sounds like the same issue and I thought I would share my experience on here. I have a 2012 with 66K miles that has been hard downshifting from 3rd to 2nd. It is a really loud, jarring bang. It had been doing this for months and then finally after a long drive I got the service wrench (orange light) to turn on after multiple hard downshifts.
I took it in to the dealer and they charged me $150 to tell me that there was an internal transmission failure, and gave me a quote for $10,000 to put in a new one, or $8000 for them to rebuild it ?
I am going to pull the transmission pan (again) and see what the magnet looks like after I cleaned it 4000 miles ago. Also going to replace solenoid A and B. I don't really expect it to resolve my issue, but it's a cheap part, and the transmission seems to shift buttery smooth otherwise, so I'm holding out hope that it is something simple. But I do fear that it is a deeper issue that will require a full rebuild or replacement....
I also have a low/rough idle which I thought might be related since the computer could be having a hard time rev-matching if it can't control the engine speed, but that seems like a stretch. Oh, and the dealer charged me another $150 to tell me that the idle speed issue would be fixed with motor mounts LOL.
In summary DON'T TAKE IT TO THE DEALERSHIP