2015 w/ delay reverse and drive
 

I have a 2015 6.7l. Just tried backing out of my driveway and it was like the tranny slipped outta gear. and then all of thew sudden it caught back up again. Threw it in drive and nothing for about 5 seconds then it shifted into drive. tried going back to reverse and same issue, nothing then shifts into gear. Saw a TSB on older models, but anyone know what's going on and if it's a driveway fix or shop fix?

AFter it's warmed up a bit it seems to be running fine. Just checked the AT fluid and it looks full on warm. Anythoughts?

I would venture to say shop fix. There are so many electronic components in transmission these days. I would go to a transmission or my choice the dealer and have them diagnose it.