Quick answer: Drag Animator State asset directly into Instructions. Set Min Activation Time. Default Camera as fallback.

Animator changes from Idle to Run. StateDrivenCamera should switch to ActionVcam. Doesn't. Instruction’s state name was typed by hand and didn't match.

The Fix

StateDrivenCamera (CM):
  Animated Target:        Player.Animator
  Layer Index:            0
  Default Camera:         IdleVcam
  Instructions:
    [0] State: Run        Vcam: ActionVcam      Activation Time: 0.1
    [1] State: Idle       Vcam: IdleVcam        Activation Time: 0.1

Drag the AnimatorState asset from the Animator window directly into the State slot — no typing, no case mistakes.

Verifying

Animator transitions; cameras follow. With typed mismatch: stays on Default.

“Drag state. Activation time. Cameras follow.”

Related Issues

For Impulse channel, see channel. For Confiner2D, see Confiner2D.

Drag state. Camera follows.