On my 2018 6.4L (46K miles) having an issue with the tranny, she shifts real hard into 4th then when it does that it just stays in 4th. if you stop then take off it will shift from 1st to 4th and stay there and overheat the tranny, no downshift or anything until you stop shut it off then start up and go again and everything is fine. This has happened quite a few times over the last two weeks. i have an appt for recalls and such on the 7th will get them to look at this. I do have a code reader might see if there are any codes that come up but just wanted to see if anyone else has had this issue or not and what to check for.