Great point as many think the range device fixes the shudder, however it just bypasses the shudder when device is enabled. The triple flush fixes it in most every occasion.

 

That's the problem I had wondering if my 2016 A8 had a shutter or problem with V4 / V8.
The confusing thing is, when trying to figure out what's really happening, there's other factors that can be mistaken for the V4 / V8 issue.
In my experience with my 2016 A8 going in and out of V4 / V8, it was Barely noticeable, if at all 90% of the time.
Cruising in V4 and giving it more throttle was instant and unnoticeable, but sometimes going uphill in V4, and giving it Light throttle, there would "sometimes" be a Split Second dead spot going into V8.
With that in mind, IMO there wasn't a problem, just the nature of the beast.
But as I mentioned in my previous post, starting at 25,000 miles with light throttle in slow traffic,.. the whole car would shudder n jerk n shake.

There's no mistaking when the "Shutter" problem is present !

But again, there's other factors that can be mistaken for an actual V4 / V8 issue
Road surface, tire misalignment, sometimes a bad tire/s when buying new, ( "ask me how I know" )
Another issue is a different subject, but has also been discussed in V4 /V8 threads, is the Staggered 19 front, 20 rear wheels.
If the tires are not perfectly balanced, there will/can be a rhythmic Vibration because they rotate at different speeds with certain highway speeds, and mistaken as a V4 / V8 problem..
In most cases, getting the tires Road Force balanced will fix that problem.
Its a problem I had, and I always though it was something with the V4 / V8, .. but its not, it was the tires.
I have 2 sets of tires, and finally realized one set had the rhythmic Vibration at highway speeds even though they're perfectly balanced according to the balancing machine.
Depending on weather temperatures and tire pressure once the tires warm up to higher, PSI it becomes less noticeable, or no vibration at all.
I then had that set Road Force balanced and now run 95 % smoother.
But with the other set just normally balanced, the car rides perfectly smooth at any speed all the time.

Bottom line, barring a Mechanical problem with the A8 transmission, the issue with V4 / V8 was the Fluid from the beginning.

 

Get the triple flush done at a GM dealer. It fixed the complaint. If it's out of warranty, you will probably be charged unless you have a dealer who has a good relationship with his District Service Mgr. My bill was almost $900, but it solved the problem.

 

The shudder is caused by the transmission fluid absorbing water like from high humid locations
it changes the viscosity of the fluid an causes the shudder. The new fluid GM specs reduces this problem.
I’ve has two c7 and the 2016 GM and dealers did not know what was going on and the replaced the tc which requires changing fluid - this worked for about
8k miles then GM had figured it out and changed the fluid.
I like a range device because my opinion is the 8 to 4 cyl operation afm system is very complex and will cause the sensation of a shudder. My 2017 gs works pretty darn good with triple flush, range device and a sonar throttle controller

 

Is it possible you were in economy mode and it was going from V8 to V4 and back? You'll feel it when you accelerate or go to steady speed. Even in my 7-speed, when it switches between modes, I feel the slightest shudder.