For the last 8 months, my 2019 Malibu has been indicating the “Shift to Park” issue. I noted there is a TSB for the item, and the resolution is to replace the transmission, which should be covered under the limited powertrain warranty… I dread trying to get this resolved, but it happens 9/10 times…
My question is why have you waited 8 months to do something about this… It should be covered under the TSB… Call the Dealer ASAP…
I haven’t looked to see if it has been updated again… That would be your job by calling the dealer… 
You probably dread getting a run-around. He said, she said … To mitigate, whenever you have a conversation with someone at the dealership, the next day write them a letter summarizing the conversation, and what you believe they told you. Snail mail your letter to them, don’t use email. And if they disagree with your summary, ask them to write you a letter explaining what it is they disagree about. In other words, keep every communication between you and dealership to a written record, signed and dated.
Note: If you think dealership will claim they never received your letter(s), you can mail them certified with return receipt. Not quite as good, but less expensive & still offers proof you mailed a letter, the post office will give you a metered receipt if you ask, showing the date and time you mailed the letter, and the zip code it was addressed to.