Brief camera jitter that resolves itself after a couple seconds

I have this problem when the game starts and the player first moves, the camera jitters really badly and then after a couple of seconds it resolves itself and is nice and smooth from then on.

I have my player movement (rb.AddForce & rb.MoveRotation) in FixedUpdate. My Parallax background movement is in Update and my Cinemachine camera is set to Smart Update. I also have my player rigidbody set to interpolate. I’ve experimented with a few different combinations but this is the closest I’ve got it to working so far.

Please can anyone tell me what I’m doing wrong?

Look at the vcam inspector when you start to play the game. In play mode, it shows how it’s updating. What does it say a) when it’s jittering, and b) when it’s smooth?

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