2017 CVT rebuild

I have a 2017 Nissan Sentra SV ,

I got it around 115000 miles and now around 122000 miles and I had to get the CVT rebuild because of affordability

These past couple months I’ve been fighting with it and realized the transmission is giving out (FIRST AND LAST CVT)

Started out with random RPM jumps , then weird shifting from 30mph and up then 60mph.

After that it had a HARD TIME switching from reverse to drive so I then got the transmission fluid flushed and replaced along with the filter ( it’s true , don’t change the fluid if it hasn’t been maintained ) and we noticed a lot of metal shavings

the car never shifted after 60MPH after the fluid change

Eventually the shifting was still HARD and the reverse gave out bc it would legit drive forward in reverse , so I took it to be rebuilt.

Talking to the mechanic he rebuild my transmission but still has hard shifting from reverse to drive and you have to slightly release the gas and press it around 60mph for it to shift. He then cleaned the valve body and still the same issue just maybe a little less.

I got a call from him and he says that the car ,in drive is sitting around 12 v so he’s guessing it’s the alternator not holding power so the transmission body module? Isn’t communicating properly. I’m not sure but if he puts in a new transmission and it still runs the same I don’t know what els it can be , maybe the fly wheel ? Maybe the fluid cooler idk

It drives and shifts from test drive, still hard on going from reverse to neutral and drive , RMP bounces (bonus … the car breaks when the acceleration peddle is released )

Any thoughts or experiences before I let him mess with it more ??