How many miles on your trans? My experience with the 545RFE has been good with the exception of the solenoid packs. They tend to fail long before anything else and often times they are overlooked by inexperienced techs and failures tend to be blamed on the torque converter and pump when the solenoid pack is the root cause. It should almost be a tune-up item at around 100k in my opinion.

Clutch Volume Index relearn simply allows the TCM to learn how long it takes to completely engage the clutch packs so that a normal engagement pattern can be established, even if the clutches are severely worn.

You might be surprised at what kind of random and intermittent failures can be caused by the solenoid pack as it ages. If your failure were a hard part like a torque converter or pump, etc.........I would think that your problem would come back immediately.

Something you may want to watch closely is the slip that is monitored by the TCM. Do you have a scanner that can monitor that parameter?

read the trans temp , if is not plausibile ..........example-18 F when warm , you have solenoid problem and can cause every strange shifting problem but you must monitor this parameter when the problem occur , BTW it seems a pressure problem

let us know if the problem return and after how many miles

I ask you the same, although I think it's unnecessary, but did you see whether there were errors in the TCM ?

I had a Nissan Pathfinder years ago that went to the dealer multiple times for random strangeness similar to what you are experiencing. I finally took it to a good friend and after about a 10 minute drive he stopped and put one more quart in the trans and it was fixed. The trans circuits must all be filled sequentially and when you are cruising in OD, all circuits are full of fluid and there is very little remaining fluid in the pan...........drop an extra qt in it. Can't hurt to try and if it works, what the hell.

Just throwing it out there.

The problem will return, and the longer I wait the worse it will get. In a 1000 miles it will uncomfortable. In 2000 miles it will almost be dangerous trying to get it to shift at 70mph/110kph. In 4000 miles I will have to keep the OD off button to keep it driving.

ok , but you do not have dTC in the TCM ? its seem fluid pressure problem

If its not a fluid or filter problem and there is no clutch slippage, then it has to be a valve problem.

It could be the solenoid pack.
But I'm thinking its one or more valves within the valve body.
Maybe a thorough disassebly and cleaning of the valve body will fix it.