to the OP: my limited research and personal experiences with this subject is that threads on this subject pop up in cycles(spring/fall mostly) and typically in places where temperature fluctuates dramatically in a matter of hours (day to day or overnight). the trans uses pressures to shift, ambient air temp affects rpms at startup, rpms at startup affect shifting... its kindve a flawed, semi complex system which yields very different behavior in all types of different conditions instead of other cars which do not have such a behavior range... as a result YOU as a user need to make sure you are doing a few things to avoid the harsh engagements, which in my experience, will result in strange shifts if driven immediately after the harsh engagements without shutting the car off..
here is what you can do:
i am willing to bet that when you turn the key on after the car has been sitting that you are not waiting the 15 seconds or so for the rpms to settle. you are probably just turning the key and going. you shouldnt do that. you gotta wait the 15 secs for the rpms to drop to whatever they drop to.. in my case slightly less than 1k rpm... dont get into a 'habit' of just waiting a few seconds and then shifting into gear though.. you actually have to watch the gauge bc when its been over 60 degrees for a week and all of a sudden its 30 degrees (or vice versa) its going to take longer for the rpms to drop, and even when they do drop it might take another second for them to stablize.. if i shift the lever while this is happening i get the delayed engagements/no engagements/slamming engagements... and if i dont immediately put it in Park and shut the motor off it will continue the wonky shifting while driving and end up throwing off long term shift strategies because the shifts are soo different that they start to reprogram the PCM's KAM & shift strategies... your best bet is to firmly put the car back in P, shut it off for a second, turn it back on, let rpms settle, shift thru all of the settings (p,n,r,d5,d4,etc) once or twice with your foot on the brake. if it fails to take any gear properly, just shut it off and repeat this until it does. dont drive it until it shifts normally with just the lever.
it is completely possible that you may have an actual issue with your trans such as low fluid or a bad solenoid. check the fluid for sure, but the solenoid does not magically get fried or whatever some people here who replace their solenoids a few times a yr will tell you. if the solenoid is fed bad data it will not behave correctly... its a computer: garbage input - garbage output. its possible that it can fail but theres a lot you can do to ensure that it has not failed and that you have another issue (namely rebooting the kam & shift strategies).
i have extensive experience on this topic.. i live in ohio where we routinely experience all 4 seasons in a 48hr period.. in addition i live in the city center and have a 6 story open air parking garage plus parking in the basement... when the wind from the surrounding buildings and natural wind get to wipping, the basement will get pressurized in addition to maintaining temperatures from the previous day/night which i have personally seen vary by as much as 30 degrees... my 05v6 goes insane when there is a huge pressure/temp diff between where it was parked overnight vs where it was driven.. ie. if its parked in the basement and it got down to 28 overnight with high wind (higher pressure), and its still 28 in the basement when i fire it up.. once i get out on the street and all of the sensors change over to the 65 degrees it is outside the car will begin shifting a bit different until it adjusts itself. and if anything factoring into a shift is even mildly out of spec it will be exacerbated in these conditions and will likely not be able to be rectified without curing the problem.
the same thing happens when it has been cold forever and then its suddenly warm for a day, or vice versa
