You're not alone! I just received the service shifter message. Haven't done much about it since I first got it yesterday afternoon. Shops are not open today, afterall it is the 4th of July.
Interesting note though...The second image you can see all the lights on my shifter are on while I am in drive. I have had this issue for a few months now. In fact, I am pretty sure that disabling the seat belt alarm started that issue. But this never triggered the service shifter message on my dash.
Also A month back I went to Jeep to get new software updates to my car and after the fact my back camera as well started having issues. I am reading that they put in a whole new shifter module to "resolve" the issue. But I don't believe they really have a fix. In fact it makes sense that if I do this it will just fail later down the line. I may just have to replace it though because I can not get the message to go away whatsoever.
For those that had it replaced. It is covered under warranty right? and how long did they take on your vehicle to replace the shifter?