+ 1 for rev lack of matching or auto service as a potential cauase
As a test, put the gearbox into sports shift mode by pushinmg the lever to the left.
Then check what speed and revs you are doing as you pull back on the lever to jump up from 1 to 2. Is it a smooth change (should be)?
Then ENSURE the speed and revs are similar to the above as you push forward on the lever to drop down from 2 to 1. Is it smooth?
If it's still a rough change 1-2 & 2-1, then do a full auto service and try the above once again, i'm curious to here the results