correct as is CH47 Ramp dosen´t move.

[-Bob-]

You are not able to move the ramp  if the gunner is sitting on the ramp. The ramp remains in the ground position and can't be moved in the middle position.

[Lord Vader]

The fact that you cannot move the ramp is intended.

However the position of the ramp will be reviewed in a future update to make it more realistic and practical for the gunner.