Renault Master 2.3 ( 2012) semi-automatic gear jerking

[CommanderKeen]

Hi!

It all started with a slight jerking when changing gear and sometimes the inability to reverse.
So I went to a mechanic to diagnose the replacement of the clutch and clutch lock.
After replacement, the car started but only with 3 gears and no reverse.
Back to the mechanic, 100 times adjusting, releasing the air, searching, changing all the oils.

After all those things and events, the gears are all operational, the car does not jerk but
1st gear the car starts normally
2nd gear it drives as if on half clutch
3rd gear halfway also on the semi-clutch and afterward the car suddenly behaves as if everything was normal and runs like new
4th 5th 6th normal

Does anyone have any ideas about what the hell is going on? Thank you in advance for your help.