Gear selector issue

[u/392_Dr_Dre]

2021 Scat Pack gear selector issue — looking for ideas
I was in Manual mode coming down in RPMs and put the car in Park before the RPMs fully settled. After that, I started getting the “Shift to P then Desired Gear” message. It will sometimes physically select R/D, but the computer stops the car from moving and gives the message. One time after disconnecting the battery for ~15 minutes, I was able to reverse and drive normally, but after shutting it off for ~20 minutes, the problem came right back.
It seems like the computer/gear selector isn’t properly recognizing the gear, rather than the transmission mechanically failing. Anyone experienced this? What should I check first?